diff --git a/src/idl_gen_ts.cpp b/src/idl_gen_ts.cpp
index c7371686b..298349d58 100644
--- a/src/idl_gen_ts.cpp
+++ b/src/idl_gen_ts.cpp
@@ -1975,8 +1975,7 @@ class TsGenerator : public BaseGenerator {
         GenDocComment(code_ptr);
         code += "static " + namer_.Method("add", field);
         code += "(builder:flatbuffers.Builder, " + argname + ":" +
-                GetArgType(imports, struct_def, field, /* allow null */ true) +
-                ") {\n";
+                GetArgType(imports, struct_def, field, false) + ") {\n";
         code += "  builder.addField" + GenWriteMethod(field.value.type) + "(";
         code += NumToString(it - struct_def.fields.vec.begin()) + ", ";
         if (field.value.type.base_type == BASE_TYPE_BOOL) { code += "+"; }
diff --git a/ts/builder.ts b/ts/builder.ts
index 4ba340352..15394cfe4 100644
--- a/ts/builder.ts
+++ b/ts/builder.ts
@@ -1,6 +1,6 @@
 import { ByteBuffer } from "./byte-buffer.js"
-import { SIZEOF_SHORT, SIZE_PREFIX_LENGTH, SIZEOF_INT, FILE_IDENTIFIER_LENGTH } from "./constants.js"
-import { Offset, IGeneratedObject } from "./types.js"
+import { FILE_IDENTIFIER_LENGTH, SIZEOF_INT, SIZEOF_SHORT, SIZE_PREFIX_LENGTH } from "./constants.js"
+import { IGeneratedObject, Offset } from "./types.js"
 
 export class Builder {
     private bb: ByteBuffer
@@ -202,42 +202,42 @@ export class Builder {
       this.writeFloat64(value);
     }
   
-    addFieldInt8(voffset: number, value: number, defaultValue: number): void {
+    addFieldInt8(voffset: number, value: number, defaultValue: number|null): void {
       if (this.force_defaults || value != defaultValue) {
         this.addInt8(value);
         this.slot(voffset);
       }
     }
   
-    addFieldInt16(voffset: number, value: number, defaultValue: number): void {
+    addFieldInt16(voffset: number, value: number, defaultValue: number|null): void {
       if (this.force_defaults || value != defaultValue) {
         this.addInt16(value);
         this.slot(voffset);
       }
     }
   
-    addFieldInt32(voffset: number, value: number, defaultValue: number): void {
+    addFieldInt32(voffset: number, value: number, defaultValue: number|null): void {
       if (this.force_defaults || value != defaultValue) {
         this.addInt32(value);
         this.slot(voffset);
       }
     }
   
-    addFieldInt64(voffset: number, value: bigint, defaultValue: bigint): void {
+    addFieldInt64(voffset: number, value: bigint, defaultValue: bigint|null): void {
       if (this.force_defaults || value !== defaultValue) {
         this.addInt64(value);
         this.slot(voffset);
       }
     }
   
-    addFieldFloat32(voffset: number, value: number, defaultValue: number): void {
+    addFieldFloat32(voffset: number, value: number, defaultValue: number|null): void {
       if (this.force_defaults || value != defaultValue) {
         this.addFloat32(value);
         this.slot(voffset);
       }
     }
   
-    addFieldFloat64(voffset: number, value: number, defaultValue: number): void {
+    addFieldFloat64(voffset: number, value: number, defaultValue: number|null): void {
       if (this.force_defaults || value != defaultValue) {
         this.addFloat64(value);
         this.slot(voffset);