diff --git a/app/assets/stylesheets/pages/diff.scss b/app/assets/stylesheets/pages/diff.scss
index 3ffe8ae304d4fd2a5191a4169be6ea69d6e14fa9..95ea49ad465088bd75e8b01931f2f6b6e4f4047b 100644
--- a/app/assets/stylesheets/pages/diff.scss
+++ b/app/assets/stylesheets/pages/diff.scss
@@ -14,7 +14,7 @@
       position: -webkit-sticky;
       position: sticky;
       top: $mr-file-header-top;
-      z-index: 220;
+      z-index: 120;
 
       &::before {
         content: '';
diff --git a/changelogs/unreleased/z-index-fix-for-diff-file-dropdown.yml b/changelogs/unreleased/z-index-fix-for-diff-file-dropdown.yml
new file mode 100644
index 0000000000000000000000000000000000000000..72108f6ab7742b07bd5295588e20d2f0652aa0af
--- /dev/null
+++ b/changelogs/unreleased/z-index-fix-for-diff-file-dropdown.yml
@@ -0,0 +1,5 @@
+---
+title: I fixed z index bug in diff page
+merge_request: 30657
+author: Faruk Can
+type: fixed