diff --git a/themes/V3/Blank/snippets/imageMask.gen.js b/themes/V3/Blank/snippets/imageMask.gen.js
index 9c2a35c2c..343cc093b 100644
--- a/themes/V3/Blank/snippets/imageMask.gen.js
+++ b/themes/V3/Blank/snippets/imageMask.gen.js
@@ -20,10 +20,10 @@ module.exports = {
 			'right'  : 270
 		}[side];
 		return dedent`
-			{{imageMaskEdge${_.random(1, 8)},--offset:0cm,--rotation:${rotation}
+			{{imageMaskEdge${_.random(1, 8)},--offset:0%,--rotation:${rotation}
 			  ![](https://i.imgur.com/GZfjDWV.png){height:100%}
 			}}
-			<!-- Use --offset to shift the mask toward or away from the page center.
+			<!-- Use --offset to shift the mask away from page center (can use cm instead of %)
 			     Use --rotation to set rotation angle in degrees. -->\n\n`;
 	},