diff --git a/impression/impression_canon.py b/impression/impression_canon.py
index 6aff0af7..e2d4ce3d 100755
--- a/impression/impression_canon.py
+++ b/impression/impression_canon.py
@@ -128,7 +128,7 @@ def _uniq_jid():
         f = file(fname,'r+')
         cur = int(f.read())+1
         f.seek(0)
-    except:
+    except (IOError,ValueError):
         cur = 0
         f = file(fname,'w')
     f.write(str(cur))