diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 8111b93074..dca533ac91 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -7734,7 +7734,7 @@ GetConfigOptionByNum(int varnum, const char **values, bool *noshow)
 				values[2] = "min";
 				break;
 			default:
-				values[2] = "";
+				values[2] = NULL;
 				break;
 		}
 	}