diff --git a/.hgignore b/.hgignore
index 030bb58b79..20acb94e67 100644
--- a/.hgignore
+++ b/.hgignore
@@ -12,6 +12,7 @@ tests/*.err
 *.idb
 *.pdb
 *.exp
+___*
 .hg
 .hgignore
 .hgtags