diff --git a/src/main/resources/update/gitbucket-core_4.0.sql b/src/main/resources/update/gitbucket-core_4.0.sql
index 12b5fcf..f97bdbc 100644
--- a/src/main/resources/update/gitbucket-core_4.0.sql
+++ b/src/main/resources/update/gitbucket-core_4.0.sql
@@ -3,7 +3,7 @@
    A.USER_NAME,
    A.REPOSITORY_NAME,
    A.ISSUE_ID,
-   IFNULL(B.COMMENT_COUNT, 0) + IFNULL(C.COMMENT_COUNT, 0) AS COMMENT_COUNT
+   COALESCE(B.COMMENT_COUNT, 0) + COALESCE(C.COMMENT_COUNT, 0) AS COMMENT_COUNT
  FROM ISSUE A
  LEFT OUTER JOIN (
    SELECT USER_NAME, REPOSITORY_NAME, ISSUE_ID, COUNT(COMMENT_ID) AS COMMENT_COUNT FROM ISSUE_COMMENT