diff --git a/src/plugins/http/src/gcJson.c b/src/plugins/http/src/gcJson.c
index 98069f434defbbda99399ee7ea4b773abc0a44b4..544a11b5fc925c8c948e26f182e5d1cbd8b1e4c3 100644
--- a/src/plugins/http/src/gcJson.c
+++ b/src/plugins/http/src/gcJson.c
@@ -125,7 +125,7 @@ bool gcBuildQueryJson(HttpContext *pContext, HttpSqlCmd *cmd, TAOS_RES *result,
 
     // for group by
     if (groupFields != -1) {
-      char target[HTTP_GC_TARGET_SIZE];
+      char target[HTTP_GC_TARGET_SIZE] = {0};
       int len;
       len = snprintf(target,HTTP_GC_TARGET_SIZE,"%s{",aliasBuffer);
       for (int i = dataFields + 1; i<num_fields; i++){