image_resize_filter.module |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/image_resize_filter.module b/image_resize_filter.module
index 02d0c0a..2a3b3ae 100644
--- a/image_resize_filter.module
+++ b/image_resize_filter.module
@@ -255,7 +255,7 @@ function image_resize_filter_get_images($settings, $text) {
 
     // Find attributes of this image tag.
     $attribute_matches = array();
-    preg_match_all('/([a-z]+)[ ]*=[ ]*"([^"]*)"/i', $img_tag, $attribute_matches);
+    preg_match_all('/([\w\-]+)[ ]*=[ ]*"([^"]*)"/i', $img_tag, $attribute_matches);
     foreach ($attribute_matches[0] as $key => $match) {
       $attribute = $attribute_matches[1][$key];
       $attribute_value = $attribute_matches[2][$key];