diff --git a/codegen/smithy-aws-typescript-codegen/src/main/java/software/amazon/smithy/aws/typescript/codegen/JsonRpcProtocolGenerator.java b/codegen/smithy-aws-typescript-codegen/src/main/java/software/amazon/smithy/aws/typescript/codegen/JsonRpcProtocolGenerator.java
index decda5d9e8393..c610a5a7f54a2 100644
--- a/codegen/smithy-aws-typescript-codegen/src/main/java/software/amazon/smithy/aws/typescript/codegen/JsonRpcProtocolGenerator.java
+++ b/codegen/smithy-aws-typescript-codegen/src/main/java/software/amazon/smithy/aws/typescript/codegen/JsonRpcProtocolGenerator.java
@@ -107,6 +107,14 @@ private DocumentMemberSerVisitor getMemberSerVisitor(GenerationContext context,
         return new JsonMemberSerVisitor(context, dataSource, getDocumentTimestampFormat());
     }
 
+    @Override
+    protected boolean writeUndefinedInputBody(GenerationContext context, OperationShape operation) {
+        TypeScriptWriter writer = context.getWriter();
+
+        writer.write("const body = '{}';");
+        return true;
+    }
+
     @Override
     protected void writeErrorCodeParser(GenerationContext context) {
         TypeScriptWriter writer = context.getWriter();