diff --git a/.hgignore b/.hgignore
index 1154332f7..101478361 100644
--- a/.hgignore
+++ b/.hgignore
@@ -7,6 +7,7 @@
 ^build/
 ^dist/
 ^tests/.coverage
+^tests/build/
 ^sphinx/pycode/Grammar.*pickle
 ^Sphinx.egg-info/
 ^doc/_build/