diff --git a/imagecache.module b/imagecache.module
index 2e5de2c..fbf0eaa 100644
--- a/imagecache.module
+++ b/imagecache.module
@@ -343,8 +343,21 @@ function imagecache_create_url($presetname, $filepath, $bypass_browser_cache = F
   $args = array('absolute' => $absolute, 'query' => empty($bypass_browser_cache) ? NULL : time());
   switch (variable_get('file_downloads', FILE_DOWNLOADS_PUBLIC)) {
     case FILE_DOWNLOADS_PUBLIC:
-      $base = $absolute ? $GLOBALS['base_url'] .'/' : '';
-      return url($base . file_directory_path() ."/imagecache/$presetname/$path", $args);
+      // Build the path including the preset name, and save a copy
+      $path = file_directory_path() .'/imagecache/'. $presetname .'/'. $path;
+      $old_path = path;
+      drupal_alter('file_url', $path);
+
+      // If hook_file_url_alter() did not change the output, then we need to add
+      // the base URL. If it did, we can presume the path needs no modification.
+      if ($path == $old_path){
+        $path = $GLOBALS['base_url'] . '/' . $path;
+      }
+
+      // Even though our path here may have been altered, and point to a CDN or
+      // something, we still want to use url() so that bypass_browser_cache works
+      return url($path, $args);
+
     case FILE_DOWNLOADS_PRIVATE:
       return url("system/files/imagecache/$presetname/$path", $args);
   }