diff --git a/wagtail/wagtailimages/models.py b/wagtail/wagtailimages/models.py
index 17e1ece86..8535199e7 100644
--- a/wagtail/wagtailimages/models.py
+++ b/wagtail/wagtailimages/models.py
@@ -243,9 +243,7 @@ class AbstractRendition(models.Model):
         )
 
     def img_tag(self):
-        return mark_safe(
-            '<img src="%s" width="%d" height="%d" alt="%s">' % (escape(self.url), self.width, self.height, escape(self.image.title))
-        )
+        return mark_safe('<img %s>' % self.attrs)
 
     class Meta:
         abstract = True