diff --git a/base/memory/ref_counted.h b/base/memory/ref_counted.h
index 1207ed4..e35264b 100644
--- a/base/memory/ref_counted.h
+++ b/base/memory/ref_counted.h
@@ -260,9 +260,10 @@
     // AddRef first so that self assignment should work
     if (p)
       p->AddRef();
-    if (ptr_ )
-      ptr_ ->Release();
+    T* old_ptr = ptr_;
     ptr_ = p;
+    if (old_ptr)
+      old_ptr ->Release();
     return *this;
   }