diff --git a/lib/utils.js b/lib/utils.js
index 270cbd6a2..23873ffc6 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -7,7 +7,7 @@ exports.isSQLite = function isSQLite (sequelize) {
 exports.getImageMimeType = function getImageMimeType (imagePath) {
   var fileExtension = /[^.]+$/.exec(imagePath)
 
-  switch (fileExtension[0]) {
+  switch (fileExtension[0].toLowerCase()) {
     case 'bmp':
       return 'image/bmp'
     case 'gif':