diff --git a/cps/static/js/kthoom.js b/cps/static/js/kthoom.js
index 8670a60d..56038fc6 100644
--- a/cps/static/js/kthoom.js
+++ b/cps/static/js/kthoom.js
@@ -146,6 +146,9 @@ kthoom.ImageFile = function(file) {
         case "jpeg":
             this.mimeType = "image/jpeg";
             break;
+        case "png":
+            this.mimeType = "image/png";
+            break;
         case "gif":
             this.mimeType = "image/gif";
             break;