--- a/mfbt/tests/TestNotNull.cpp
+++ b/mfbt/tests/TestNotNull.cpp
@@ -62,20 +62,21 @@ public:
     if (mRefCnt > mMaxRefCnt) {
       mMaxRefCnt = mRefCnt;
     }
     return mRefCnt;
   }
 
   uint32_t Release() {
     CHECK(mRefCnt > 0);
-    if (mRefCnt == 1) {
+    mRefCnt--;
+    if (mRefCnt == 0) {
       delete this;
+      return 0;
     }
-    mRefCnt--;
     return mRefCnt;
   }
 };
 
 void f_i(int* aPtr) {}
 void f_my(MyPtr<int> aPtr) {}
 
 void f_nni(NotNull<int*> aPtr) {}