--- a/etherlab/etherlab.py	Mon Oct 01 13:43:50 2018 +0300
+++ b/etherlab/etherlab.py	Mon Oct 01 14:13:05 2018 +0300
@@ -254,7 +254,7 @@
                     for device in self.devices_xpath(self.modules_infos):
                         device_group = device.getGroupType()
                         if device_group not in vendor_category["groups"]:
-                            raise ValueError("Not such group \"%\"" % device_group)
+                            raise ValueError("Not such group \"%s\"" % device_group)
                         vendor_category["groups"][device_group]["devices"].append(
                             (device.getType().getcontent(), device))
 

--- a/tests/tools/check_source.sh	Mon Oct 01 13:43:50 2018 +0300
+++ b/tests/tools/check_source.sh	Mon Oct 01 14:13:05 2018 +0300
@@ -290,6 +290,7 @@
     enable=$enable,W0111          # (assign-to-new-keyword) Name async will become a keyword in Python 3.7
     enable=$enable,W0623          # (redefine-in-handler) Redefining name 'X' from outer scope (line Y) in exception handler
     enable=$enable,E1310          # (bad-str-strip-call) Suspicious argument in str.strip call
+    enable=$enable,E1300          # (bad-format-character) Unsupported format character '"' (0x22) at index 17
     enable=$enable,W0106          # (expression-not-assigned) Expression "X" is assigned to nothing
     enable=$enable,E1136          # (unsubscriptable-object) Value 'X' is unsubscriptable
     enable=$enable,E0602          # (undefined-variable) Undefined variable 'X'