diff --git a/src/REAXFF/reaxff_tool_box.cpp b/src/REAXFF/reaxff_tool_box.cpp
index aa6f831e95..e39a6c6654 100644
--- a/src/REAXFF/reaxff_tool_box.cpp
+++ b/src/REAXFF/reaxff_tool_box.cpp
@@ -101,6 +101,6 @@ void sfree(void *ptr)
   if (ptr == nullptr) return;
 
   free(ptr);
-  ptr = nullptr;
+  ptr = nullptr;  // NOTE: this has no effect
 }
 }    // namespace ReaxFF