diff --git a/src/previous-map.js b/src/previous-map.js
index ffc1f79..2e41f8d 100644
--- a/src/previous-map.js
+++ b/src/previous-map.js
@@ -31,7 +31,7 @@ export default class PreviousMap {
     }
 
     loadAnnotation(css) {
-        let match = css.match(/\/\*\s*# sourceMappingURL=(.*)\s*\*\//);
+        let match = css.match(/\/\*\s*# sourceMappingURL=((?:(?!sourceMappingURL=).)*)\s*\*\//);
         if ( match ) this.annotation = match[1].trim();
     }