diff --git a/packages/block-editor/src/components/block-variation-transforms/style.scss b/packages/block-editor/src/components/block-variation-transforms/style.scss
index afdc95917f7ad6..2a02afdf6b7476 100644
--- a/packages/block-editor/src/components/block-variation-transforms/style.scss
+++ b/packages/block-editor/src/components/block-variation-transforms/style.scss
@@ -20,7 +20,7 @@
 
 		&:focus:not(:disabled) {
 			border-color: var(--wp-admin-theme-color);
-			box-shadow: 0 0 0 (var(--wp-admin-border-width-focus) - $border-width) var(--wp-admin-theme-color);
+			box-shadow: 0 0 0 calc(var(--wp-admin-border-width-focus) - #{ $border-width }) var(--wp-admin-theme-color);
 		}
 
 		svg {