diff --git a/packages/react-native-codegen/src/parsers/flow/modules/index.js b/packages/react-native-codegen/src/parsers/flow/modules/index.js
index 36ffbbead3ad9b..2944905d1e7869 100644
--- a/packages/react-native-codegen/src/parsers/flow/modules/index.js
+++ b/packages/react-native-codegen/src/parsers/flow/modules/index.js
@@ -179,6 +179,7 @@ function translateTypeAnnotation(
         );
         if (indexers.length > 0) {
           // check the property type to prevent developers from using unsupported types
+          // the return value from `translateTypeAnnotation` is unused
           const propertyType = indexers[0].value;
           translateTypeAnnotation(
             hasteModuleName,
@@ -265,8 +266,9 @@ function translateTypeAnnotation(
     case 'MixedTypeAnnotation': {
       if (cxxOnly) {
         return emitMixed(nullable);
+      } else {
+        return emitObject(nullable);
       }
-      // Fallthrough
     }
     default: {
       throw new UnsupportedTypeAnnotationParserError(
diff --git a/packages/react-native-codegen/src/parsers/typescript/modules/index.js b/packages/react-native-codegen/src/parsers/typescript/modules/index.js
index 71a904544d213c..25922bf4108210 100644
--- a/packages/react-native-codegen/src/parsers/typescript/modules/index.js
+++ b/packages/react-native-codegen/src/parsers/typescript/modules/index.js
@@ -198,6 +198,7 @@ function translateTypeAnnotation(
         );
         if (indexSignatures.length > 0) {
           // check the property type to prevent developers from using unsupported types
+          // the return value from `translateTypeAnnotation` is unused
           const propertyType = indexSignatures[0].typeAnnotation;
           translateTypeAnnotation(
             hasteModuleName,