diff --git a/tools/detect_targets.py b/tools/detect_targets.py
index b6407ae93a..eef1a2dc33 100644
--- a/tools/detect_targets.py
+++ b/tools/detect_targets.py
@@ -79,7 +79,7 @@ def main():
 
         count = 0
         for mut in muts.values():
-            if re.match(mcu_filter, mut['mcu']):
+            if re.match(mcu_filter, mut['mcu'] or "Unknown"):
                 interface_version = get_interface_version(mut['disk'])
                 print ""
                 print "[mbed] Detected %s, port %s, mounted %s, interface version %s:" % \