--- a/hgext/largefiles/overrides.py	Wed Jan 18 13:41:03 2012 +0100
+++ b/hgext/largefiles/overrides.py	Wed Jan 18 14:19:43 2012 +0100
@@ -720,6 +720,10 @@
         getdata = ctx[f].data
         if lfutil.isstandin(f):
             path = lfutil.findfile(repo, getdata().strip())
+            if path is None:
+                raise util.Abort(
+                    _('largefile %s not found in repo store or system cache')
+                    % lfutil.splitstandin(f))
             f = lfutil.splitstandin(f)
 
             def getdatafn():