diff --git a/virtualsmartcard/src/vpicc/virtualsmartcard/cards/Iso7816.py b/virtualsmartcard/src/vpicc/virtualsmartcard/cards/Iso7816.py
index 62cdcf8..633e230 100644
--- a/virtualsmartcard/src/vpicc/virtualsmartcard/cards/Iso7816.py
+++ b/virtualsmartcard/src/vpicc/virtualsmartcard/cards/Iso7816.py
@@ -303,7 +303,7 @@ class Iso7816OS(SmartcardOS):
             answer = self.formatResult(Iso7816OS.seekable(c.ins), c.effective_Le, result, sw, sm)
         except SwError as e:
             logging.info(e.message)
-            import traceback
+            import traceback, sys
             traceback.print_exception(*sys.exc_info())
             sw = e.sw
             result = ""
diff --git a/virtualsmartcard/src/vpicc/virtualsmartcard/cards/Relay.py b/virtualsmartcard/src/vpicc/virtualsmartcard/cards/Relay.py
index 704600c..5788457 100644
--- a/virtualsmartcard/src/vpicc/virtualsmartcard/cards/Relay.py
+++ b/virtualsmartcard/src/vpicc/virtualsmartcard/cards/Relay.py
@@ -18,7 +18,7 @@
 #
 
 from virtualsmartcard.VirtualSmartcard import SmartcardOS
-import smartcard, logging
+import smartcard, logging, sys
 
 
 class RelayOS(SmartcardOS):
diff --git a/virtualsmartcard/src/vpicc/virtualsmartcard/cards/nPA.py b/virtualsmartcard/src/vpicc/virtualsmartcard/cards/nPA.py
index 164795d..2c960bb 100644
--- a/virtualsmartcard/src/vpicc/virtualsmartcard/cards/nPA.py
+++ b/virtualsmartcard/src/vpicc/virtualsmartcard/cards/nPA.py
@@ -81,7 +81,7 @@ class NPAOS(Iso7816OS):
                 sw, result = self.SAM.protect_result(sw, result)
             except SwError as e:
                 logging.info(e.message)
-                import traceback
+                import traceback, sys
                 traceback.print_exception(*sys.exc_info())
                 sw = e.sw
                 result = ""