diff --git a/src/calibre/gui2/__init__.py b/src/calibre/gui2/__init__.py
index c7306e7abc..5818eb46e3 100644
--- a/src/calibre/gui2/__init__.py
+++ b/src/calibre/gui2/__init__.py
@@ -539,10 +539,18 @@ class FileIconProvider(QFileIconProvider):
 
     def __init__(self):
         QFileIconProvider.__init__(self)
-        self.icons = {}
-        for key in self.__class__.ICONS.keys():
-            self.icons[key] = I('mimetypes/')+self.__class__.ICONS[key]+'.png'
-        self.icons['calibre'] = I('lt.png')
+        upath, bpath = I('mimetypes'), I('mimetypes', allow_user_override=False)
+        if upath != bpath:
+            # User has chosen to override mimetype icons
+            path_map = {v:I('mimetypes/%s.png' % v) for v in set(self.ICONS.itervalues())}
+            for uicon in glob.glob(os.path.join(upath, '*.png')):
+                ukey = os.path.basename(uicon).rpartition('.')[0].lower()
+                if ukey not in path_map:
+                    path_map[ukey] = uicon
+        else:
+            path_map = {v:os.path.join(bpath, v + '.png') for v in set(self.ICONS.itervalues())}
+        self.icons = {k:path_map[v] for k, v in self.ICONS.iteritems()}
+        self.icons['calibre'] = I('lt.png', allow_user_override=False)
         for i in ('dir', 'default', 'zero'):
             self.icons[i] = QIcon(self.icons[i])