diff --git a/check_lang_compatibility.py b/check_lang_compatibility.py
--- a/check_lang_compatibility.py
+++ b/check_lang_compatibility.py
@@ -58,8 +58,12 @@ def get_langfile_rev(name, rev):
@return: Lines wit string names.
@rtype: C{list} of C{str}
"""
+ # Copy the environment, and add HGPLAIN
+ env = dict(kv for kv in os.environ.items())
+ env['HGPLAIN'] = ''
+
cmd = ['hg', 'cat', '-r', rev, name]
- txt = subprocess.check_output(cmd, universal_newlines=True, env={'HGPLAIN':''})
+ txt = subprocess.check_output(cmd, universal_newlines=True, env=env)
lines = []
for line in txt.split('\n'):