diff --git a/pykat/exceptions.py b/pykat/exceptions.py
index 1c28f65d51eb8d9c22190930da4220e635503a38..c1f620be084d1e200c3f0c14a8edafc77e565ccf 100644
--- a/pykat/exceptions.py
+++ b/pykat/exceptions.py
@@ -1,4 +1,5 @@
 import exceptions
+import os
 
 class BasePyKatException(Exception):
     def __init__(self, msg):
diff --git a/pykat/finesse.py b/pykat/finesse.py
index ac5fb4c7f061dffeda1431245d56b0aae916d5a5..a40f85813920ef8dc4e5c006f4acac657d58c5e8 100644
--- a/pykat/finesse.py
+++ b/pykat/finesse.py
@@ -400,7 +400,7 @@ class kat(object):
                 self.__finesse_dir = os.environ.get('FINESSE_DIR')
                 
                 if self.__finesse_dir == None :
-                    raise MissingFinesseEnvVar()
+                    raise pkex.MissingFinesseEnvVar()
             else:
                 self.__finesse_dir = self.__katdir
                 
@@ -416,7 +416,7 @@ class kat(object):
             
             # check if kat file exists and it is executable by user        
             if not (os.path.isfile(kat_exec) and os.access(kat_exec, os.X_OK)):
-                raise MissingFinesse()
+                raise pkex.MissingFinesse()
                 
             if self.verbose: print "--------------------------------------------------------------"
             if self.verbose: print "Running kat - Started at " + str(start)