diff --git a/fdroidserver/update.py b/fdroidserver/update.py
index 9c6c21f3..83f069fa 100644
--- a/fdroidserver/update.py
+++ b/fdroidserver/update.py
@@ -1086,7 +1086,7 @@ def _get_apk_icons_src(apkfile, icon_name):
 
     """
     icons_src = dict()
-    density_re = re.compile('^res/(.*)/' + icon_name + '\.(png|xml)$')
+    density_re = re.compile('^res/(.*)/{}\.(png|xml)$'.format(icon_name))
     with zipfile.ZipFile(apkfile) as zf:
         for filename in zf.namelist():
             m = density_re.match(filename)
diff --git a/tests/update.TestCase b/tests/update.TestCase
index 03391c18..9c60adfd 100755
--- a/tests/update.TestCase
+++ b/tests/update.TestCase
@@ -647,6 +647,16 @@ class UpdateTest(unittest.TestCase):
         with self.assertRaises(fdroidserver.exception.FDroidException):
             fdroidserver.update.has_known_vulnerability('janus.apk')
 
+    def test_get_apk_icon_when_src_is_none(self):
+        config = dict()
+        fdroidserver.common.fill_config_defaults(config)
+        fdroidserver.common.config = config
+        fdroidserver.update.config = config
+
+        # pylint: disable=protected-access
+        icons_src = fdroidserver.update._get_apk_icons_src('urzip-release.apk', None)
+        assert icons_src == {}
+
 
 if __name__ == "__main__":
     parser = optparse.OptionParser()