diff --git a/samples/monster_generated.h b/samples/monster_generated.h
index a0facac96..f5ed15196 100644
--- a/samples/monster_generated.h
+++ b/samples/monster_generated.h
@@ -327,6 +327,10 @@ struct Monster FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
   void *mutable_equipped() {
     return GetPointer<void *>(VT_EQUIPPED);
   }
+  template<typename T> T *mutable_equipped_as();
+  MyGame::Sample::Weapon *mutable_equipped_as_Weapon() {
+    return equipped_type() == MyGame::Sample::Equipment_Weapon ? static_cast<MyGame::Sample::Weapon *>(mutable_equipped()) : nullptr;
+  }
   const ::flatbuffers::Vector<const MyGame::Sample::Vec3 *> *path() const {
     return GetPointer<const ::flatbuffers::Vector<const MyGame::Sample::Vec3 *> *>(VT_PATH);
   }
@@ -363,6 +367,10 @@ template<> inline const MyGame::Sample::Weapon *Monster::equipped_as<MyGame::Sam
   return equipped_as_Weapon();
 }
 
+template<> inline MyGame::Sample::Weapon *Monster::mutable_equipped_as<MyGame::Sample::Weapon>() {
+  return mutable_equipped_as_Weapon();
+}
+
 struct MonsterBuilder {
   typedef Monster Table;
   ::flatbuffers::FlatBufferBuilder &fbb_;
diff --git a/src/idl_gen_cpp.cpp b/src/idl_gen_cpp.cpp
index 6207071f3..ef490858d 100644
--- a/src/idl_gen_cpp.cpp
+++ b/src/idl_gen_cpp.cpp
@@ -2625,14 +2625,18 @@ class CppGenerator : public BaseGenerator {
     code_ += "  }";
   }
 
-  void GenTableUnionAsGetters(const FieldDef& field) {
+  void GenTableUnionAsGetters(const FieldDef& field, bool is_mutable) {
     const auto& type = field.value.type;
     auto u = type.enum_def;
 
+    code_.SetValue("MUTABLE_EXT", is_mutable ? "" : " const");
+    code_.SetValue("MUTABLE", is_mutable ? "mutable_" : "");
+
     if (!type.enum_def->uses_multiple_type_instances)
       code_ +=
-          "  template<typename T> "
-          "const T *{{NULLABLE_EXT}}{{FIELD_NAME}}_as() const;";
+          "  template<typename T>"
+          "{{MUTABLE_EXT}} T *{{MUTABLE}}{{NULLABLE_EXT}}{{FIELD_NAME}}_as()"
+          "{{MUTABLE_EXT}};";
 
     for (auto u_it = u->Vals().begin(); u_it != u->Vals().end(); ++u_it) {
       auto& ev = **u_it;
@@ -2646,15 +2650,19 @@ class CppGenerator : public BaseGenerator {
                      EscapeKeyword(Name(field) + UnionTypeFieldSuffix()));
       code_.SetValue("U_ELEMENT_TYPE", WrapInNameSpace(u->defined_namespace,
                                                        GetEnumValUse(*u, ev)));
-      code_.SetValue("U_FIELD_TYPE", "const " + full_struct_name + " *");
+      code_.SetValue("U_FIELD_TYPE",
+                     (is_mutable ? "" : "const ") + full_struct_name + " *");
       code_.SetValue("U_FIELD_NAME", Name(field) + "_as_" + Name(ev));
       code_.SetValue("U_NULLABLE", NullableExtension());
 
       // `const Type *union_name_asType() const` accessor.
-      code_ += "  {{U_FIELD_TYPE}}{{U_NULLABLE}}{{U_FIELD_NAME}}() const {";
+      // and `Type *mutable_union_name_asType()` accessor.
+      code_ +=
+          "  {{U_FIELD_TYPE}}{{U_NULLABLE}}{{MUTABLE}}{{U_FIELD_NAME}}()"
+          "{{MUTABLE_EXT}} {";
       code_ +=
           "    return {{U_GET_TYPE}}() == {{U_ELEMENT_TYPE}} ? "
-          "static_cast<{{U_FIELD_TYPE}}>({{FIELD_NAME}}()) "
+          "static_cast<{{U_FIELD_TYPE}}>({{MUTABLE}}{{FIELD_NAME}}()) "
           ": nullptr;";
       code_ += "  }";
     }
@@ -2709,7 +2717,7 @@ class CppGenerator : public BaseGenerator {
     }
 
     if (type.base_type == BASE_TYPE_UNION) {
-      GenTableUnionAsGetters(field);
+      GenTableUnionAsGetters(field, false);
     }
   }
 
@@ -2898,6 +2906,11 @@ class CppGenerator : public BaseGenerator {
       code_ += "  {{FIELD_TYPE}}mutable_{{FIELD_NAME}}() {";
       code_ += "    return {{FIELD_VALUE}};";
       code_ += "  }";
+
+      // mutable union accessors
+      if (type.base_type == BASE_TYPE_UNION) {
+        GenTableUnionAsGetters(field, true);
+      }
     }
   }
 
@@ -3074,6 +3087,7 @@ class CppGenerator : public BaseGenerator {
         code_.SetValue("U_FIELD_NAME", Name(*field) + "_as_" + Name(ev));
 
         // `template<> const T *union_name_as<T>() const` accessor.
+        // and `template<> T *mutable_union_name_as<T>()` accessor.
         code_ +=
             "template<> "
             "inline {{U_FIELD_TYPE}}{{STRUCT_NAME}}::{{FIELD_NAME}}_as"
@@ -3081,6 +3095,20 @@ class CppGenerator : public BaseGenerator {
         code_ += "  return {{U_FIELD_NAME}}();";
         code_ += "}";
         code_ += "";
+
+        if (opts_.mutable_buffer) {
+          code_.SetValue("U_FIELD_TYPE", full_struct_name + " *");
+          code_.SetValue("U_FIELD_NAME",
+                         "mutable_" + Name(*field) + "_as_" + Name(ev));
+          code_ +=
+              "template<> "
+              "inline {{U_FIELD_TYPE}}"
+              "{{STRUCT_NAME}}::mutable_{{FIELD_NAME}}_as"
+              "<{{U_ELEMENT_NAME}}>() {";
+          code_ += "  return {{U_FIELD_NAME}}();";
+          code_ += "}";
+          code_ += "";
+        }
       }
     }
 
diff --git a/tests/cpp17/generated_cpp17/monster_test_generated.h b/tests/cpp17/generated_cpp17/monster_test_generated.h
index c056e38f4..063858c92 100644
--- a/tests/cpp17/generated_cpp17/monster_test_generated.h
+++ b/tests/cpp17/generated_cpp17/monster_test_generated.h
@@ -1484,6 +1484,16 @@ struct Monster FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
   void *mutable_test() {
     return GetPointer<void *>(VT_TEST);
   }
+  template<typename T> T *mutable_test_as();
+  MyGame::Example::Monster *mutable_test_as_Monster() {
+    return test_type() == MyGame::Example::Any::Monster ? static_cast<MyGame::Example::Monster *>(mutable_test()) : nullptr;
+  }
+  MyGame::Example::TestSimpleTableWithEnum *mutable_test_as_TestSimpleTableWithEnum() {
+    return test_type() == MyGame::Example::Any::TestSimpleTableWithEnum ? static_cast<MyGame::Example::TestSimpleTableWithEnum *>(mutable_test()) : nullptr;
+  }
+  MyGame::Example2::Monster *mutable_test_as_MyGame_Example2_Monster() {
+    return test_type() == MyGame::Example::Any::MyGame_Example2_Monster ? static_cast<MyGame::Example2::Monster *>(mutable_test()) : nullptr;
+  }
   const ::flatbuffers::Vector<const MyGame::Example::Test *> *test4() const {
     return GetPointer<const ::flatbuffers::Vector<const MyGame::Example::Test *> *>(VT_TEST4);
   }
@@ -1719,6 +1729,16 @@ struct Monster FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
   void *mutable_any_unique() {
     return GetPointer<void *>(VT_ANY_UNIQUE);
   }
+  template<typename T> T *mutable_any_unique_as();
+  MyGame::Example::Monster *mutable_any_unique_as_M() {
+    return any_unique_type() == MyGame::Example::AnyUniqueAliases::M ? static_cast<MyGame::Example::Monster *>(mutable_any_unique()) : nullptr;
+  }
+  MyGame::Example::TestSimpleTableWithEnum *mutable_any_unique_as_TS() {
+    return any_unique_type() == MyGame::Example::AnyUniqueAliases::TS ? static_cast<MyGame::Example::TestSimpleTableWithEnum *>(mutable_any_unique()) : nullptr;
+  }
+  MyGame::Example2::Monster *mutable_any_unique_as_M2() {
+    return any_unique_type() == MyGame::Example::AnyUniqueAliases::M2 ? static_cast<MyGame::Example2::Monster *>(mutable_any_unique()) : nullptr;
+  }
   MyGame::Example::AnyAmbiguousAliases any_ambiguous_type() const {
     return static_cast<MyGame::Example::AnyAmbiguousAliases>(GetField<uint8_t>(VT_ANY_AMBIGUOUS_TYPE, 0));
   }
@@ -1737,6 +1757,15 @@ struct Monster FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
   void *mutable_any_ambiguous() {
     return GetPointer<void *>(VT_ANY_AMBIGUOUS);
   }
+  MyGame::Example::Monster *mutable_any_ambiguous_as_M1() {
+    return any_ambiguous_type() == MyGame::Example::AnyAmbiguousAliases::M1 ? static_cast<MyGame::Example::Monster *>(mutable_any_ambiguous()) : nullptr;
+  }
+  MyGame::Example::Monster *mutable_any_ambiguous_as_M2() {
+    return any_ambiguous_type() == MyGame::Example::AnyAmbiguousAliases::M2 ? static_cast<MyGame::Example::Monster *>(mutable_any_ambiguous()) : nullptr;
+  }
+  MyGame::Example::Monster *mutable_any_ambiguous_as_M3() {
+    return any_ambiguous_type() == MyGame::Example::AnyAmbiguousAliases::M3 ? static_cast<MyGame::Example::Monster *>(mutable_any_ambiguous()) : nullptr;
+  }
   const ::flatbuffers::Vector<MyGame::Example::Color> *vector_of_enums() const {
     return GetPointer<const ::flatbuffers::Vector<MyGame::Example::Color> *>(VT_VECTOR_OF_ENUMS);
   }
@@ -2008,26 +2037,50 @@ template<> inline const MyGame::Example::Monster *Monster::test_as<MyGame::Examp
   return test_as_Monster();
 }
 
+template<> inline MyGame::Example::Monster *Monster::mutable_test_as<MyGame::Example::Monster>() {
+  return mutable_test_as_Monster();
+}
+
 template<> inline const MyGame::Example::TestSimpleTableWithEnum *Monster::test_as<MyGame::Example::TestSimpleTableWithEnum>() const {
   return test_as_TestSimpleTableWithEnum();
 }
 
+template<> inline MyGame::Example::TestSimpleTableWithEnum *Monster::mutable_test_as<MyGame::Example::TestSimpleTableWithEnum>() {
+  return mutable_test_as_TestSimpleTableWithEnum();
+}
+
 template<> inline const MyGame::Example2::Monster *Monster::test_as<MyGame::Example2::Monster>() const {
   return test_as_MyGame_Example2_Monster();
 }
 
+template<> inline MyGame::Example2::Monster *Monster::mutable_test_as<MyGame::Example2::Monster>() {
+  return mutable_test_as_MyGame_Example2_Monster();
+}
+
 template<> inline const MyGame::Example::Monster *Monster::any_unique_as<MyGame::Example::Monster>() const {
   return any_unique_as_M();
 }
 
+template<> inline MyGame::Example::Monster *Monster::mutable_any_unique_as<MyGame::Example::Monster>() {
+  return mutable_any_unique_as_M();
+}
+
 template<> inline const MyGame::Example::TestSimpleTableWithEnum *Monster::any_unique_as<MyGame::Example::TestSimpleTableWithEnum>() const {
   return any_unique_as_TS();
 }
 
+template<> inline MyGame::Example::TestSimpleTableWithEnum *Monster::mutable_any_unique_as<MyGame::Example::TestSimpleTableWithEnum>() {
+  return mutable_any_unique_as_TS();
+}
+
 template<> inline const MyGame::Example2::Monster *Monster::any_unique_as<MyGame::Example2::Monster>() const {
   return any_unique_as_M2();
 }
 
+template<> inline MyGame::Example2::Monster *Monster::mutable_any_unique_as<MyGame::Example2::Monster>() {
+  return mutable_any_unique_as_M2();
+}
+
 struct MonsterBuilder {
   typedef Monster Table;
   ::flatbuffers::FlatBufferBuilder &fbb_;
diff --git a/tests/cpp17/generated_cpp17/union_vector_generated.h b/tests/cpp17/generated_cpp17/union_vector_generated.h
index e81f1d6a3..e73bb1a8f 100644
--- a/tests/cpp17/generated_cpp17/union_vector_generated.h
+++ b/tests/cpp17/generated_cpp17/union_vector_generated.h
@@ -598,6 +598,24 @@ struct Movie FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
   void *mutable_main_character() {
     return GetPointer<void *>(VT_MAIN_CHARACTER);
   }
+  Attacker *mutable_main_character_as_MuLan() {
+    return main_character_type() == Character::MuLan ? static_cast<Attacker *>(mutable_main_character()) : nullptr;
+  }
+  Rapunzel *mutable_main_character_as_Rapunzel() {
+    return main_character_type() == Character::Rapunzel ? static_cast<Rapunzel *>(mutable_main_character()) : nullptr;
+  }
+  BookReader *mutable_main_character_as_Belle() {
+    return main_character_type() == Character::Belle ? static_cast<BookReader *>(mutable_main_character()) : nullptr;
+  }
+  BookReader *mutable_main_character_as_BookFan() {
+    return main_character_type() == Character::BookFan ? static_cast<BookReader *>(mutable_main_character()) : nullptr;
+  }
+  ::flatbuffers::String *mutable_main_character_as_Other() {
+    return main_character_type() == Character::Other ? static_cast<::flatbuffers::String *>(mutable_main_character()) : nullptr;
+  }
+  ::flatbuffers::String *mutable_main_character_as_Unused() {
+    return main_character_type() == Character::Unused ? static_cast<::flatbuffers::String *>(mutable_main_character()) : nullptr;
+  }
   const ::flatbuffers::Vector<Character> *characters_type() const {
     return GetPointer<const ::flatbuffers::Vector<Character> *>(VT_CHARACTERS_TYPE);
   }
diff --git a/tests/monster_test_generated.h b/tests/monster_test_generated.h
index 594670baa..6a9f2bb3b 100644
--- a/tests/monster_test_generated.h
+++ b/tests/monster_test_generated.h
@@ -1480,6 +1480,16 @@ struct Monster FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
   void *mutable_test() {
     return GetPointer<void *>(VT_TEST);
   }
+  template<typename T> T *mutable_test_as();
+  MyGame::Example::Monster *mutable_test_as_Monster() {
+    return test_type() == MyGame::Example::Any_Monster ? static_cast<MyGame::Example::Monster *>(mutable_test()) : nullptr;
+  }
+  MyGame::Example::TestSimpleTableWithEnum *mutable_test_as_TestSimpleTableWithEnum() {
+    return test_type() == MyGame::Example::Any_TestSimpleTableWithEnum ? static_cast<MyGame::Example::TestSimpleTableWithEnum *>(mutable_test()) : nullptr;
+  }
+  MyGame::Example2::Monster *mutable_test_as_MyGame_Example2_Monster() {
+    return test_type() == MyGame::Example::Any_MyGame_Example2_Monster ? static_cast<MyGame::Example2::Monster *>(mutable_test()) : nullptr;
+  }
   const ::flatbuffers::Vector<const MyGame::Example::Test *> *test4() const {
     return GetPointer<const ::flatbuffers::Vector<const MyGame::Example::Test *> *>(VT_TEST4);
   }
@@ -1715,6 +1725,16 @@ struct Monster FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
   void *mutable_any_unique() {
     return GetPointer<void *>(VT_ANY_UNIQUE);
   }
+  template<typename T> T *mutable_any_unique_as();
+  MyGame::Example::Monster *mutable_any_unique_as_M() {
+    return any_unique_type() == MyGame::Example::AnyUniqueAliases_M ? static_cast<MyGame::Example::Monster *>(mutable_any_unique()) : nullptr;
+  }
+  MyGame::Example::TestSimpleTableWithEnum *mutable_any_unique_as_TS() {
+    return any_unique_type() == MyGame::Example::AnyUniqueAliases_TS ? static_cast<MyGame::Example::TestSimpleTableWithEnum *>(mutable_any_unique()) : nullptr;
+  }
+  MyGame::Example2::Monster *mutable_any_unique_as_M2() {
+    return any_unique_type() == MyGame::Example::AnyUniqueAliases_M2 ? static_cast<MyGame::Example2::Monster *>(mutable_any_unique()) : nullptr;
+  }
   MyGame::Example::AnyAmbiguousAliases any_ambiguous_type() const {
     return static_cast<MyGame::Example::AnyAmbiguousAliases>(GetField<uint8_t>(VT_ANY_AMBIGUOUS_TYPE, 0));
   }
@@ -1733,6 +1753,15 @@ struct Monster FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
   void *mutable_any_ambiguous() {
     return GetPointer<void *>(VT_ANY_AMBIGUOUS);
   }
+  MyGame::Example::Monster *mutable_any_ambiguous_as_M1() {
+    return any_ambiguous_type() == MyGame::Example::AnyAmbiguousAliases_M1 ? static_cast<MyGame::Example::Monster *>(mutable_any_ambiguous()) : nullptr;
+  }
+  MyGame::Example::Monster *mutable_any_ambiguous_as_M2() {
+    return any_ambiguous_type() == MyGame::Example::AnyAmbiguousAliases_M2 ? static_cast<MyGame::Example::Monster *>(mutable_any_ambiguous()) : nullptr;
+  }
+  MyGame::Example::Monster *mutable_any_ambiguous_as_M3() {
+    return any_ambiguous_type() == MyGame::Example::AnyAmbiguousAliases_M3 ? static_cast<MyGame::Example::Monster *>(mutable_any_ambiguous()) : nullptr;
+  }
   const ::flatbuffers::Vector<uint8_t> *vector_of_enums() const {
     return GetPointer<const ::flatbuffers::Vector<uint8_t> *>(VT_VECTOR_OF_ENUMS);
   }
@@ -1939,26 +1968,50 @@ template<> inline const MyGame::Example::Monster *Monster::test_as<MyGame::Examp
   return test_as_Monster();
 }
 
+template<> inline MyGame::Example::Monster *Monster::mutable_test_as<MyGame::Example::Monster>() {
+  return mutable_test_as_Monster();
+}
+
 template<> inline const MyGame::Example::TestSimpleTableWithEnum *Monster::test_as<MyGame::Example::TestSimpleTableWithEnum>() const {
   return test_as_TestSimpleTableWithEnum();
 }
 
+template<> inline MyGame::Example::TestSimpleTableWithEnum *Monster::mutable_test_as<MyGame::Example::TestSimpleTableWithEnum>() {
+  return mutable_test_as_TestSimpleTableWithEnum();
+}
+
 template<> inline const MyGame::Example2::Monster *Monster::test_as<MyGame::Example2::Monster>() const {
   return test_as_MyGame_Example2_Monster();
 }
 
+template<> inline MyGame::Example2::Monster *Monster::mutable_test_as<MyGame::Example2::Monster>() {
+  return mutable_test_as_MyGame_Example2_Monster();
+}
+
 template<> inline const MyGame::Example::Monster *Monster::any_unique_as<MyGame::Example::Monster>() const {
   return any_unique_as_M();
 }
 
+template<> inline MyGame::Example::Monster *Monster::mutable_any_unique_as<MyGame::Example::Monster>() {
+  return mutable_any_unique_as_M();
+}
+
 template<> inline const MyGame::Example::TestSimpleTableWithEnum *Monster::any_unique_as<MyGame::Example::TestSimpleTableWithEnum>() const {
   return any_unique_as_TS();
 }
 
+template<> inline MyGame::Example::TestSimpleTableWithEnum *Monster::mutable_any_unique_as<MyGame::Example::TestSimpleTableWithEnum>() {
+  return mutable_any_unique_as_TS();
+}
+
 template<> inline const MyGame::Example2::Monster *Monster::any_unique_as<MyGame::Example2::Monster>() const {
   return any_unique_as_M2();
 }
 
+template<> inline MyGame::Example2::Monster *Monster::mutable_any_unique_as<MyGame::Example2::Monster>() {
+  return mutable_any_unique_as_M2();
+}
+
 struct MonsterBuilder {
   typedef Monster Table;
   ::flatbuffers::FlatBufferBuilder &fbb_;
diff --git a/tests/monster_test_suffix/ext_only/monster_test_generated.hpp b/tests/monster_test_suffix/ext_only/monster_test_generated.hpp
index b3db30d3b..d2bdfce6c 100644
--- a/tests/monster_test_suffix/ext_only/monster_test_generated.hpp
+++ b/tests/monster_test_suffix/ext_only/monster_test_generated.hpp
@@ -1471,6 +1471,16 @@ struct Monster FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
   void *mutable_test() {
     return GetPointer<void *>(VT_TEST);
   }
+  template<typename T> T *mutable_test_as();
+  MyGame::Example::Monster *mutable_test_as_Monster() {
+    return test_type() == MyGame::Example::Any_Monster ? static_cast<MyGame::Example::Monster *>(mutable_test()) : nullptr;
+  }
+  MyGame::Example::TestSimpleTableWithEnum *mutable_test_as_TestSimpleTableWithEnum() {
+    return test_type() == MyGame::Example::Any_TestSimpleTableWithEnum ? static_cast<MyGame::Example::TestSimpleTableWithEnum *>(mutable_test()) : nullptr;
+  }
+  MyGame::Example2::Monster *mutable_test_as_MyGame_Example2_Monster() {
+    return test_type() == MyGame::Example::Any_MyGame_Example2_Monster ? static_cast<MyGame::Example2::Monster *>(mutable_test()) : nullptr;
+  }
   const ::flatbuffers::Vector<const MyGame::Example::Test *> *test4() const {
     return GetPointer<const ::flatbuffers::Vector<const MyGame::Example::Test *> *>(VT_TEST4);
   }
@@ -1706,6 +1716,16 @@ struct Monster FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
   void *mutable_any_unique() {
     return GetPointer<void *>(VT_ANY_UNIQUE);
   }
+  template<typename T> T *mutable_any_unique_as();
+  MyGame::Example::Monster *mutable_any_unique_as_M() {
+    return any_unique_type() == MyGame::Example::AnyUniqueAliases_M ? static_cast<MyGame::Example::Monster *>(mutable_any_unique()) : nullptr;
+  }
+  MyGame::Example::TestSimpleTableWithEnum *mutable_any_unique_as_TS() {
+    return any_unique_type() == MyGame::Example::AnyUniqueAliases_TS ? static_cast<MyGame::Example::TestSimpleTableWithEnum *>(mutable_any_unique()) : nullptr;
+  }
+  MyGame::Example2::Monster *mutable_any_unique_as_M2() {
+    return any_unique_type() == MyGame::Example::AnyUniqueAliases_M2 ? static_cast<MyGame::Example2::Monster *>(mutable_any_unique()) : nullptr;
+  }
   MyGame::Example::AnyAmbiguousAliases any_ambiguous_type() const {
     return static_cast<MyGame::Example::AnyAmbiguousAliases>(GetField<uint8_t>(VT_ANY_AMBIGUOUS_TYPE, 0));
   }
@@ -1724,6 +1744,15 @@ struct Monster FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
   void *mutable_any_ambiguous() {
     return GetPointer<void *>(VT_ANY_AMBIGUOUS);
   }
+  MyGame::Example::Monster *mutable_any_ambiguous_as_M1() {
+    return any_ambiguous_type() == MyGame::Example::AnyAmbiguousAliases_M1 ? static_cast<MyGame::Example::Monster *>(mutable_any_ambiguous()) : nullptr;
+  }
+  MyGame::Example::Monster *mutable_any_ambiguous_as_M2() {
+    return any_ambiguous_type() == MyGame::Example::AnyAmbiguousAliases_M2 ? static_cast<MyGame::Example::Monster *>(mutable_any_ambiguous()) : nullptr;
+  }
+  MyGame::Example::Monster *mutable_any_ambiguous_as_M3() {
+    return any_ambiguous_type() == MyGame::Example::AnyAmbiguousAliases_M3 ? static_cast<MyGame::Example::Monster *>(mutable_any_ambiguous()) : nullptr;
+  }
   const ::flatbuffers::Vector<uint8_t> *vector_of_enums() const {
     return GetPointer<const ::flatbuffers::Vector<uint8_t> *>(VT_VECTOR_OF_ENUMS);
   }
@@ -1930,26 +1959,50 @@ template<> inline const MyGame::Example::Monster *Monster::test_as<MyGame::Examp
   return test_as_Monster();
 }
 
+template<> inline MyGame::Example::Monster *Monster::mutable_test_as<MyGame::Example::Monster>() {
+  return mutable_test_as_Monster();
+}
+
 template<> inline const MyGame::Example::TestSimpleTableWithEnum *Monster::test_as<MyGame::Example::TestSimpleTableWithEnum>() const {
   return test_as_TestSimpleTableWithEnum();
 }
 
+template<> inline MyGame::Example::TestSimpleTableWithEnum *Monster::mutable_test_as<MyGame::Example::TestSimpleTableWithEnum>() {
+  return mutable_test_as_TestSimpleTableWithEnum();
+}
+
 template<> inline const MyGame::Example2::Monster *Monster::test_as<MyGame::Example2::Monster>() const {
   return test_as_MyGame_Example2_Monster();
 }
 
+template<> inline MyGame::Example2::Monster *Monster::mutable_test_as<MyGame::Example2::Monster>() {
+  return mutable_test_as_MyGame_Example2_Monster();
+}
+
 template<> inline const MyGame::Example::Monster *Monster::any_unique_as<MyGame::Example::Monster>() const {
   return any_unique_as_M();
 }
 
+template<> inline MyGame::Example::Monster *Monster::mutable_any_unique_as<MyGame::Example::Monster>() {
+  return mutable_any_unique_as_M();
+}
+
 template<> inline const MyGame::Example::TestSimpleTableWithEnum *Monster::any_unique_as<MyGame::Example::TestSimpleTableWithEnum>() const {
   return any_unique_as_TS();
 }
 
+template<> inline MyGame::Example::TestSimpleTableWithEnum *Monster::mutable_any_unique_as<MyGame::Example::TestSimpleTableWithEnum>() {
+  return mutable_any_unique_as_TS();
+}
+
 template<> inline const MyGame::Example2::Monster *Monster::any_unique_as<MyGame::Example2::Monster>() const {
   return any_unique_as_M2();
 }
 
+template<> inline MyGame::Example2::Monster *Monster::mutable_any_unique_as<MyGame::Example2::Monster>() {
+  return mutable_any_unique_as_M2();
+}
+
 struct MonsterBuilder {
   typedef Monster Table;
   ::flatbuffers::FlatBufferBuilder &fbb_;
diff --git a/tests/monster_test_suffix/filesuffix_only/monster_test_suffix.h b/tests/monster_test_suffix/filesuffix_only/monster_test_suffix.h
index b3db30d3b..d2bdfce6c 100644
--- a/tests/monster_test_suffix/filesuffix_only/monster_test_suffix.h
+++ b/tests/monster_test_suffix/filesuffix_only/monster_test_suffix.h
@@ -1471,6 +1471,16 @@ struct Monster FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
   void *mutable_test() {
     return GetPointer<void *>(VT_TEST);
   }
+  template<typename T> T *mutable_test_as();
+  MyGame::Example::Monster *mutable_test_as_Monster() {
+    return test_type() == MyGame::Example::Any_Monster ? static_cast<MyGame::Example::Monster *>(mutable_test()) : nullptr;
+  }
+  MyGame::Example::TestSimpleTableWithEnum *mutable_test_as_TestSimpleTableWithEnum() {
+    return test_type() == MyGame::Example::Any_TestSimpleTableWithEnum ? static_cast<MyGame::Example::TestSimpleTableWithEnum *>(mutable_test()) : nullptr;
+  }
+  MyGame::Example2::Monster *mutable_test_as_MyGame_Example2_Monster() {
+    return test_type() == MyGame::Example::Any_MyGame_Example2_Monster ? static_cast<MyGame::Example2::Monster *>(mutable_test()) : nullptr;
+  }
   const ::flatbuffers::Vector<const MyGame::Example::Test *> *test4() const {
     return GetPointer<const ::flatbuffers::Vector<const MyGame::Example::Test *> *>(VT_TEST4);
   }
@@ -1706,6 +1716,16 @@ struct Monster FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
   void *mutable_any_unique() {
     return GetPointer<void *>(VT_ANY_UNIQUE);
   }
+  template<typename T> T *mutable_any_unique_as();
+  MyGame::Example::Monster *mutable_any_unique_as_M() {
+    return any_unique_type() == MyGame::Example::AnyUniqueAliases_M ? static_cast<MyGame::Example::Monster *>(mutable_any_unique()) : nullptr;
+  }
+  MyGame::Example::TestSimpleTableWithEnum *mutable_any_unique_as_TS() {
+    return any_unique_type() == MyGame::Example::AnyUniqueAliases_TS ? static_cast<MyGame::Example::TestSimpleTableWithEnum *>(mutable_any_unique()) : nullptr;
+  }
+  MyGame::Example2::Monster *mutable_any_unique_as_M2() {
+    return any_unique_type() == MyGame::Example::AnyUniqueAliases_M2 ? static_cast<MyGame::Example2::Monster *>(mutable_any_unique()) : nullptr;
+  }
   MyGame::Example::AnyAmbiguousAliases any_ambiguous_type() const {
     return static_cast<MyGame::Example::AnyAmbiguousAliases>(GetField<uint8_t>(VT_ANY_AMBIGUOUS_TYPE, 0));
   }
@@ -1724,6 +1744,15 @@ struct Monster FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
   void *mutable_any_ambiguous() {
     return GetPointer<void *>(VT_ANY_AMBIGUOUS);
   }
+  MyGame::Example::Monster *mutable_any_ambiguous_as_M1() {
+    return any_ambiguous_type() == MyGame::Example::AnyAmbiguousAliases_M1 ? static_cast<MyGame::Example::Monster *>(mutable_any_ambiguous()) : nullptr;
+  }
+  MyGame::Example::Monster *mutable_any_ambiguous_as_M2() {
+    return any_ambiguous_type() == MyGame::Example::AnyAmbiguousAliases_M2 ? static_cast<MyGame::Example::Monster *>(mutable_any_ambiguous()) : nullptr;
+  }
+  MyGame::Example::Monster *mutable_any_ambiguous_as_M3() {
+    return any_ambiguous_type() == MyGame::Example::AnyAmbiguousAliases_M3 ? static_cast<MyGame::Example::Monster *>(mutable_any_ambiguous()) : nullptr;
+  }
   const ::flatbuffers::Vector<uint8_t> *vector_of_enums() const {
     return GetPointer<const ::flatbuffers::Vector<uint8_t> *>(VT_VECTOR_OF_ENUMS);
   }
@@ -1930,26 +1959,50 @@ template<> inline const MyGame::Example::Monster *Monster::test_as<MyGame::Examp
   return test_as_Monster();
 }
 
+template<> inline MyGame::Example::Monster *Monster::mutable_test_as<MyGame::Example::Monster>() {
+  return mutable_test_as_Monster();
+}
+
 template<> inline const MyGame::Example::TestSimpleTableWithEnum *Monster::test_as<MyGame::Example::TestSimpleTableWithEnum>() const {
   return test_as_TestSimpleTableWithEnum();
 }
 
+template<> inline MyGame::Example::TestSimpleTableWithEnum *Monster::mutable_test_as<MyGame::Example::TestSimpleTableWithEnum>() {
+  return mutable_test_as_TestSimpleTableWithEnum();
+}
+
 template<> inline const MyGame::Example2::Monster *Monster::test_as<MyGame::Example2::Monster>() const {
   return test_as_MyGame_Example2_Monster();
 }
 
+template<> inline MyGame::Example2::Monster *Monster::mutable_test_as<MyGame::Example2::Monster>() {
+  return mutable_test_as_MyGame_Example2_Monster();
+}
+
 template<> inline const MyGame::Example::Monster *Monster::any_unique_as<MyGame::Example::Monster>() const {
   return any_unique_as_M();
 }
 
+template<> inline MyGame::Example::Monster *Monster::mutable_any_unique_as<MyGame::Example::Monster>() {
+  return mutable_any_unique_as_M();
+}
+
 template<> inline const MyGame::Example::TestSimpleTableWithEnum *Monster::any_unique_as<MyGame::Example::TestSimpleTableWithEnum>() const {
   return any_unique_as_TS();
 }
 
+template<> inline MyGame::Example::TestSimpleTableWithEnum *Monster::mutable_any_unique_as<MyGame::Example::TestSimpleTableWithEnum>() {
+  return mutable_any_unique_as_TS();
+}
+
 template<> inline const MyGame::Example2::Monster *Monster::any_unique_as<MyGame::Example2::Monster>() const {
   return any_unique_as_M2();
 }
 
+template<> inline MyGame::Example2::Monster *Monster::mutable_any_unique_as<MyGame::Example2::Monster>() {
+  return mutable_any_unique_as_M2();
+}
+
 struct MonsterBuilder {
   typedef Monster Table;
   ::flatbuffers::FlatBufferBuilder &fbb_;
diff --git a/tests/monster_test_suffix/monster_test_suffix.hpp b/tests/monster_test_suffix/monster_test_suffix.hpp
index b3db30d3b..d2bdfce6c 100644
--- a/tests/monster_test_suffix/monster_test_suffix.hpp
+++ b/tests/monster_test_suffix/monster_test_suffix.hpp
@@ -1471,6 +1471,16 @@ struct Monster FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
   void *mutable_test() {
     return GetPointer<void *>(VT_TEST);
   }
+  template<typename T> T *mutable_test_as();
+  MyGame::Example::Monster *mutable_test_as_Monster() {
+    return test_type() == MyGame::Example::Any_Monster ? static_cast<MyGame::Example::Monster *>(mutable_test()) : nullptr;
+  }
+  MyGame::Example::TestSimpleTableWithEnum *mutable_test_as_TestSimpleTableWithEnum() {
+    return test_type() == MyGame::Example::Any_TestSimpleTableWithEnum ? static_cast<MyGame::Example::TestSimpleTableWithEnum *>(mutable_test()) : nullptr;
+  }
+  MyGame::Example2::Monster *mutable_test_as_MyGame_Example2_Monster() {
+    return test_type() == MyGame::Example::Any_MyGame_Example2_Monster ? static_cast<MyGame::Example2::Monster *>(mutable_test()) : nullptr;
+  }
   const ::flatbuffers::Vector<const MyGame::Example::Test *> *test4() const {
     return GetPointer<const ::flatbuffers::Vector<const MyGame::Example::Test *> *>(VT_TEST4);
   }
@@ -1706,6 +1716,16 @@ struct Monster FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
   void *mutable_any_unique() {
     return GetPointer<void *>(VT_ANY_UNIQUE);
   }
+  template<typename T> T *mutable_any_unique_as();
+  MyGame::Example::Monster *mutable_any_unique_as_M() {
+    return any_unique_type() == MyGame::Example::AnyUniqueAliases_M ? static_cast<MyGame::Example::Monster *>(mutable_any_unique()) : nullptr;
+  }
+  MyGame::Example::TestSimpleTableWithEnum *mutable_any_unique_as_TS() {
+    return any_unique_type() == MyGame::Example::AnyUniqueAliases_TS ? static_cast<MyGame::Example::TestSimpleTableWithEnum *>(mutable_any_unique()) : nullptr;
+  }
+  MyGame::Example2::Monster *mutable_any_unique_as_M2() {
+    return any_unique_type() == MyGame::Example::AnyUniqueAliases_M2 ? static_cast<MyGame::Example2::Monster *>(mutable_any_unique()) : nullptr;
+  }
   MyGame::Example::AnyAmbiguousAliases any_ambiguous_type() const {
     return static_cast<MyGame::Example::AnyAmbiguousAliases>(GetField<uint8_t>(VT_ANY_AMBIGUOUS_TYPE, 0));
   }
@@ -1724,6 +1744,15 @@ struct Monster FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
   void *mutable_any_ambiguous() {
     return GetPointer<void *>(VT_ANY_AMBIGUOUS);
   }
+  MyGame::Example::Monster *mutable_any_ambiguous_as_M1() {
+    return any_ambiguous_type() == MyGame::Example::AnyAmbiguousAliases_M1 ? static_cast<MyGame::Example::Monster *>(mutable_any_ambiguous()) : nullptr;
+  }
+  MyGame::Example::Monster *mutable_any_ambiguous_as_M2() {
+    return any_ambiguous_type() == MyGame::Example::AnyAmbiguousAliases_M2 ? static_cast<MyGame::Example::Monster *>(mutable_any_ambiguous()) : nullptr;
+  }
+  MyGame::Example::Monster *mutable_any_ambiguous_as_M3() {
+    return any_ambiguous_type() == MyGame::Example::AnyAmbiguousAliases_M3 ? static_cast<MyGame::Example::Monster *>(mutable_any_ambiguous()) : nullptr;
+  }
   const ::flatbuffers::Vector<uint8_t> *vector_of_enums() const {
     return GetPointer<const ::flatbuffers::Vector<uint8_t> *>(VT_VECTOR_OF_ENUMS);
   }
@@ -1930,26 +1959,50 @@ template<> inline const MyGame::Example::Monster *Monster::test_as<MyGame::Examp
   return test_as_Monster();
 }
 
+template<> inline MyGame::Example::Monster *Monster::mutable_test_as<MyGame::Example::Monster>() {
+  return mutable_test_as_Monster();
+}
+
 template<> inline const MyGame::Example::TestSimpleTableWithEnum *Monster::test_as<MyGame::Example::TestSimpleTableWithEnum>() const {
   return test_as_TestSimpleTableWithEnum();
 }
 
+template<> inline MyGame::Example::TestSimpleTableWithEnum *Monster::mutable_test_as<MyGame::Example::TestSimpleTableWithEnum>() {
+  return mutable_test_as_TestSimpleTableWithEnum();
+}
+
 template<> inline const MyGame::Example2::Monster *Monster::test_as<MyGame::Example2::Monster>() const {
   return test_as_MyGame_Example2_Monster();
 }
 
+template<> inline MyGame::Example2::Monster *Monster::mutable_test_as<MyGame::Example2::Monster>() {
+  return mutable_test_as_MyGame_Example2_Monster();
+}
+
 template<> inline const MyGame::Example::Monster *Monster::any_unique_as<MyGame::Example::Monster>() const {
   return any_unique_as_M();
 }
 
+template<> inline MyGame::Example::Monster *Monster::mutable_any_unique_as<MyGame::Example::Monster>() {
+  return mutable_any_unique_as_M();
+}
+
 template<> inline const MyGame::Example::TestSimpleTableWithEnum *Monster::any_unique_as<MyGame::Example::TestSimpleTableWithEnum>() const {
   return any_unique_as_TS();
 }
 
+template<> inline MyGame::Example::TestSimpleTableWithEnum *Monster::mutable_any_unique_as<MyGame::Example::TestSimpleTableWithEnum>() {
+  return mutable_any_unique_as_TS();
+}
+
 template<> inline const MyGame::Example2::Monster *Monster::any_unique_as<MyGame::Example2::Monster>() const {
   return any_unique_as_M2();
 }
 
+template<> inline MyGame::Example2::Monster *Monster::mutable_any_unique_as<MyGame::Example2::Monster>() {
+  return mutable_any_unique_as_M2();
+}
+
 struct MonsterBuilder {
   typedef Monster Table;
   ::flatbuffers::FlatBufferBuilder &fbb_;
diff --git a/tests/namespace_test/namespace_test2_generated.h b/tests/namespace_test/namespace_test2_generated.h
index 99c661057..c6ceb6781 100644
--- a/tests/namespace_test/namespace_test2_generated.h
+++ b/tests/namespace_test/namespace_test2_generated.h
@@ -120,6 +120,10 @@ struct TableInFirstNS FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
   void *mutable_foo_union() {
     return GetPointer<void *>(VT_FOO_UNION);
   }
+  template<typename T> T *mutable_foo_union_as();
+  NamespaceA::NamespaceB::TableInNestedNS *mutable_foo_union_as_TableInNestedNS() {
+    return foo_union_type() == NamespaceA::NamespaceB::UnionInNestedNS_TableInNestedNS ? static_cast<NamespaceA::NamespaceB::TableInNestedNS *>(mutable_foo_union()) : nullptr;
+  }
   const NamespaceA::NamespaceB::StructInNestedNS *foo_struct() const {
     return GetStruct<const NamespaceA::NamespaceB::StructInNestedNS *>(VT_FOO_STRUCT);
   }
@@ -147,6 +151,10 @@ template<> inline const NamespaceA::NamespaceB::TableInNestedNS *TableInFirstNS:
   return foo_union_as_TableInNestedNS();
 }
 
+template<> inline NamespaceA::NamespaceB::TableInNestedNS *TableInFirstNS::mutable_foo_union_as<NamespaceA::NamespaceB::TableInNestedNS>() {
+  return mutable_foo_union_as_TableInNestedNS();
+}
+
 struct TableInFirstNSBuilder {
   typedef TableInFirstNS Table;
   ::flatbuffers::FlatBufferBuilder &fbb_;
diff --git a/tests/union_vector/union_vector_generated.h b/tests/union_vector/union_vector_generated.h
index 1117efd80..12bbb4ae9 100644
--- a/tests/union_vector/union_vector_generated.h
+++ b/tests/union_vector/union_vector_generated.h
@@ -614,6 +614,24 @@ struct Movie FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
   void *mutable_main_character() {
     return GetPointer<void *>(VT_MAIN_CHARACTER);
   }
+  Attacker *mutable_main_character_as_MuLan() {
+    return main_character_type() == Character_MuLan ? static_cast<Attacker *>(mutable_main_character()) : nullptr;
+  }
+  Rapunzel *mutable_main_character_as_Rapunzel() {
+    return main_character_type() == Character_Rapunzel ? static_cast<Rapunzel *>(mutable_main_character()) : nullptr;
+  }
+  BookReader *mutable_main_character_as_Belle() {
+    return main_character_type() == Character_Belle ? static_cast<BookReader *>(mutable_main_character()) : nullptr;
+  }
+  BookReader *mutable_main_character_as_BookFan() {
+    return main_character_type() == Character_BookFan ? static_cast<BookReader *>(mutable_main_character()) : nullptr;
+  }
+  ::flatbuffers::String *mutable_main_character_as_Other() {
+    return main_character_type() == Character_Other ? static_cast<::flatbuffers::String *>(mutable_main_character()) : nullptr;
+  }
+  ::flatbuffers::String *mutable_main_character_as_Unused() {
+    return main_character_type() == Character_Unused ? static_cast<::flatbuffers::String *>(mutable_main_character()) : nullptr;
+  }
   const ::flatbuffers::Vector<uint8_t> *characters_type() const {
     return GetPointer<const ::flatbuffers::Vector<uint8_t> *>(VT_CHARACTERS_TYPE);
   }