diff --git a/packages/ckeditor5-math/theme/mathform.css b/packages/ckeditor5-math/theme/mathform.css
index 6a15c852a0..9537cdbb0d 100644
--- a/packages/ckeditor5-math/theme/mathform.css
+++ b/packages/ckeditor5-math/theme/mathform.css
@@ -186,7 +186,7 @@
 	border-radius: var(--ck-border-radius, 6px);
 	font-size: var(--ck-font-size-base);
 	box-sizing: border-box;
-	background: var(--ck-color-input-background,) !important;
+	background: var(--ck-color-input-background) !important;
 	color: var(--ck-color-input-text, inherit);
 	outline: 3px solid transparent;
 	outline-offset: 6px;
@@ -202,7 +202,7 @@
 
 .ck-math-view .ck-labeled-field-view textarea:hover,
 .ck-math-view .ck-labeled-field-view textarea:focus {
-	background: var(--ck-color-input-background, ) !important;
+	background: var(--ck-color-input-background) !important;
 	color: var(--ck-color-input-text, inherit) !important;
 	outline: none !important;
 	box-shadow: none !important;