diff --git a/src/jdk.jdwp.agent/share/native/libjdwp/invoker.c b/src/jdk.jdwp.agent/share/native/libjdwp/invoker.c
index 8e2981d9fa..db92663610 100644
--- a/src/jdk.jdwp.agent/share/native/libjdwp/invoker.c
+++ b/src/jdk.jdwp.agent/share/native/libjdwp/invoker.c
@@ -241,6 +241,10 @@ deleteGlobalArgumentRefs(JNIEnv *env, InvokeRequest *request)
         argIndex++;
         argumentTag = nextArgumentTypeTag(&cursor);
     }
+
+    JDI_ASSERT_MSG(request->methodSignature != NULL, "methodSignature is NULL");
+    jvmtiDeallocate(request->methodSignature);
+    request->methodSignature = NULL;
 }
 
 static jvmtiError
@@ -281,6 +285,7 @@ fillInvokeRequest(JNIEnv *env, InvokeRequest *request,
     /*
      * Squirrel away the method signature
      */
+    JDI_ASSERT_MSG(request->methodSignature == NULL, "Request methodSignature not null");
     error = methodSignature(method, NULL, &request->methodSignature,  NULL);
     if (error != JVMTI_ERROR_NONE) {
         return error;