diff --git a/interop/src/cpp/DeserializerBase.h b/interop/src/cpp/DeserializerBase.h
index 7f62a8768b5b73acca635d776a24f49e0eb08eb2..40612bcc1833cbf5cb8373dd6d525919be85a6e5 100644
--- a/interop/src/cpp/DeserializerBase.h
+++ b/interop/src/cpp/DeserializerBase.h
@@ -53,6 +53,7 @@ inline const char *tagName(InteropTag tag)
     return "OBJECT";
   }
   INTEROP_FATAL("Fatal error");
+  return nullptr;
 }
 
 inline const char *tagNameExact(InteropTag tag)
@@ -75,6 +76,7 @@ inline const char *tagNameExact(InteropTag tag)
     return "INTEROP_TAG_OBJECT";
   }
   INTEROP_FATAL("Fatal error");
+  return nullptr;
 }
 
 inline InteropFunction makeArkFunctionFromId(InteropInt32 id) {