diff --git a/gui/scyther-gui.py b/gui/scyther-gui.py
index d20be43..2108baf 100755
--- a/gui/scyther-gui.py
+++ b/gui/scyther-gui.py
@@ -44,6 +44,7 @@ version number."""
 
         keyfound = False
         try:
+            import sys
             if sys.environment[key] == data:
                 keyfound = True
         except: