diff --git a/IkiWiki/Plugin/img.pm b/IkiWiki/Plugin/img.pm
index 2375ead89..bd527c8c8 100644
--- a/IkiWiki/Plugin/img.pm
+++ b/IkiWiki/Plugin/img.pm
@@ -156,10 +156,7 @@ sub preprocess (@) {
 		$imgurl="$config{url}/$imglink";
 	}
 
-	if (exists $params{class}) {
-		$params{class}.=" img";
-	}
-	else {
+	if (! exists $params{class}) {
 		$params{class}="img";
 	}
 
diff --git a/debian/changelog b/debian/changelog
index 12cc90b11..5433ba05f 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -14,6 +14,8 @@ ikiwiki (3.20100927) UNRELEASED; urgency=low
   * websetup: Fix defaults of checkboxes in advanced mode.
   * monotone: Fix recentchanges page when the srcdir is not at the top
     of the monotone workspace. Thanks, tommyd.
+  * img: If a class is specified, don't also put the img in the img
+    class.
 
  -- Joey Hess <joeyh@debian.org>  Wed, 29 Sep 2010 11:58:23 -0400
 
diff --git a/doc/bugs/class_parameter_of_img_directive_behave_not_as_documented.mdwn b/doc/bugs/class_parameter_of_img_directive_behave_not_as_documented.mdwn
index 10ba15066..e7797765f 100644
--- a/doc/bugs/class_parameter_of_img_directive_behave_not_as_documented.mdwn
+++ b/doc/bugs/class_parameter_of_img_directive_behave_not_as_documented.mdwn
@@ -27,3 +27,5 @@ I would prefer if the `img` class were only added if no class attribute is
 passed.
 
 If you keep the current behaviour, please document it.
+
+> [[done]] --[[Joey]]