diff --git a/source/util/src/tcompare.c b/source/util/src/tcompare.c
index d845e5aed7..679490abac 100644
--- a/source/util/src/tcompare.c
+++ b/source/util/src/tcompare.c
@@ -1235,7 +1235,7 @@ void DestoryThreadLocalRegComp() {
   if (NULL != pOldPattern) {
     regfree(&pRegex);
     taosMemoryFree(pOldPattern);
-    pOldPattern == NULL;
+    pOldPattern = NULL;
   }
 }