diff --git a/mode/python.py b/mode/python.py
index 7b2eb6b..5926741 100644
--- a/mode/python.py
+++ b/mode/python.py
@@ -228,8 +228,9 @@ class PythonSetLib(method.Method):
 class PythonCheckSyntax(method.Method):
     '''Check the syntax of the current python file'''
     def _execute(self, w, **vargs):
-        syspath = list(sys.path)
-        sys.path.insert(0, w.mode.pythonlib)
+        if w.mode.pythonlib not in sys.path:
+            sys.path = list(sys.path)
+            sys.path.insert(0, w.mode.pythonlib)
         source = w.buffer.make_string()
         try:
             code = compile(source, w.buffer.path, 'exec')
@@ -237,7 +238,6 @@ class PythonCheckSyntax(method.Method):
         except Exception, e:
             output = traceback.format_exc()
             w.application.data_buffer("*PythonSyntax*", output, switch_to=True)
-        sys.path = syspath
 
 class PythonDictCleanup(method.Method):
     '''Align assignment blocks and literal dictionaries'''