diff --git a/css-masking-1/Overview.bs b/css-masking-1/Overview.bs
index 604320b8..5ae5370a 100644
--- a/css-masking-1/Overview.bs
+++ b/css-masking-1/Overview.bs
@@ -1023,7 +1023,7 @@ The 'mask-mode' and 'mask-type' properties must have no affect on the <a>mask bo
 
 <pre class=propdef>
 Name: mask-border-slice
-Value: [ <<number>> | <<percentage>> ]{1,4} fill?
+Value: [ <<number>> | <<percentage>> ]{1,4} && fill?
 Initial: 0
 Applies to: All elements. In SVG, it applies to <a>container elements</a> excluding the <a element>defs</a> element, all <a>graphics elements</a> and the <a element>use</a> element
 Inherited: no