diff --git a/Tools/freeze/modulefinder.py b/Tools/freeze/modulefinder.py
index ddead22..7260614 100644
--- a/Tools/freeze/modulefinder.py
+++ b/Tools/freeze/modulefinder.py
@@ -249,7 +249,7 @@
         elif type == imp.PY_COMPILED:
             if fp.read(4) != imp.get_magic():
                 self.msgout(2, "raise ImportError: Bad magic number", pathname)
-                raise ImportError, "Bad magic number in %s", pathname
+                raise ImportError, "Bad magic number in %s" % pathname
             fp.read(4)
             co = marshal.load(fp)
         else: