--- a/src/pyams_file/skin/templates/picture.pt	Fri Dec 28 10:56:13 2018 +0100
+++ b/src/pyams_file/skin/templates/picture.pt	Wed Jan 16 13:50:29 2019 +0100
@@ -44,8 +44,12 @@
 	<source tal:condition="not:lg_width"
 			media="(min-width: 1200px)"
 			srcset="/--static--/pyams_skin/img/dot.png" />
-	<!-- fallback image -->
-	<img style="width: 100%;" class="${css_class}"
-		 tal:define="timestamp tales:timestamp(image)"
-		 alt="${alt}" src="${image_url}?_=${timestamp}" />
+	<tal:if condition="def_width">
+		<!-- fallback image -->
+		<img style="width: 100%;" class="${css_class}"
+			 tal:define="width str(round(1200 / 12 * def_width));
+						 thumb thumbnails.get_thumbnail(def_thumb + ':w' + width);
+						 timestamp tales:timestamp(thumb);"
+			 alt="${alt}" src="${image_url}/++thumb++${def_thumb}:w${width}?_=${timestamp}" />
+	</tal:if>
 </picture>