diff --git a/src/utils.js b/src/utils.js
index 335c2df6e..f4aed49a1 100644
--- a/src/utils.js
+++ b/src/utils.js
@@ -228,6 +228,6 @@ function moveElement( parent, child ) {
 	child.style.position = 'absolute';
 	child.style.left = left + 'px';
 	child.style.top = top + 'px';
-	child.style.zIndex = 'var(--ck-z-modal)';
+	child.style.zIndex = 'var(--ck-z-panel)';
 	child.style.pointerEvents = 'none';
 }
diff --git a/theme/mathform.css b/theme/mathform.css
index 8f3a70c9c..3b7b4047f 100644
--- a/theme/mathform.css
+++ b/theme/mathform.css
@@ -31,5 +31,5 @@
 }
 
 .ck.ck-toolbar-container {
-	z-index: calc(var(--ck-z-modal) + 2);
+	z-index: calc(var(--ck-z-panel) + 2);
 }