diff --git a/aprs/IS.py b/aprs/IS.py
index 3aead51..301de9b 100644
--- a/aprs/IS.py
+++ b/aprs/IS.py
@@ -163,7 +163,7 @@ class IS(object):
                             callback(line)
                         else:
                             callback(parse(line))
-            except KeyboardInterrupt:
+            except (KeyboardInterrupt, SystemExit):
                 raise
             except (ConnectionDrop, ConnectionError):
                 self.close()
diff --git a/aprs/version.py b/aprs/version.py
index 59e5a0b..0e4f51c 100644
--- a/aprs/version.py
+++ b/aprs/version.py
@@ -1 +1 @@
-__version__ = '0.6.21'
+__version__ = '0.6.22'