diff --git a/select2.js b/select2.js
index 0bb4feaf..1a70d036 100644
--- a/select2.js
+++ b/select2.js
@@ -1567,7 +1567,7 @@ the specific language governing permissions and limitations under the Apache Lic
                         attrs = style.split(';');
                         for (i = 0, l = attrs.length; i < l; i = i + 1) {
                             matches = attrs[i].replace(/\s/g, '')
-                                .match(/width:(([-+]?([0-9]*\.)?[0-9]+)(px|em|ex|%|in|cm|mm|pt|pc))/);
+                                .match(/width:(([-+]?([0-9]*\.)?[0-9]+)(px|em|ex|%|in|cm|mm|pt|pc))/i);
                             if (matches !== null && matches.length >= 1)
                                 return matches[1];
                         }