diff --git a/src/idl_parser.cpp b/src/idl_parser.cpp
index 9911fab0c..4c60fd7d7 100644
--- a/src/idl_parser.cpp
+++ b/src/idl_parser.cpp
@@ -457,6 +457,10 @@ uoffset_t Parser::ParseTable(const StructDef &struct_def) {
                             || struct_def.fields.vec[fieldn] != field)) {
        Error("struct field appearing out of order: " + name);
     }
+    for (auto it = field_stack_.rbegin();
+             it != field_stack_.rbegin() + fieldn; ++it) {
+      if (it->second == field) Error("field already set: " + name);
+    }
     Expect(':');
     Value val = field->value;
     ParseAnyValue(val, field);
diff --git a/tests/test.cpp b/tests/test.cpp
index 03955e331..4cd4fd1e5 100644
--- a/tests/test.cpp
+++ b/tests/test.cpp
@@ -490,6 +490,7 @@ void ErrorTest() {
   TestError("union Z { X } struct X { Y:int; }", "only tables");
   TestError("table X { Y:[int]; YLength:int; }", "clash");
   TestError("table X { Y:string = 1; }", "scalar");
+  TestError("table X { Y:byte; } root_type X; { Y:1, Y:2 }", "already set");
 }
 
 // Additional parser testing not covered elsewhere.