diff --git a/gramps/gen/plug/docgen/treedoc.py b/gramps/gen/plug/docgen/treedoc.py
index d770f9a1b..7c92ee1d5 100644
--- a/gramps/gen/plug/docgen/treedoc.py
+++ b/gramps/gen/plug/docgen/treedoc.py
@@ -47,6 +47,8 @@ from ...constfunc import win
 from ...config import config
 from ...const import GRAMPS_LOCALE as glocale
 _ = glocale.translation.gettext
+from ...utils.grampslocale import GrampsLocale
+_locale = GrampsLocale(lang='en_US')
 
 #-------------------------------------------------------------------------
 #
@@ -339,6 +341,8 @@ class TreeDocBase(BaseDoc, TreeDoc):
         self.write(0, '\\usepackage[%s,%s]{geometry}\n' % (paper, margin))
         self.write(0, '\\usepackage[all]{genealogytree}\n')
         self.write(0, '\\usepackage{color}\n')
+        lang_en = _locale._get_language_string(glocale.language[0])
+        self.write(0, '\\gtrset{language=%s}\n' % lang_en.lower())
         self.write(0, '\\begin{document}\n')
 
         if self.nodecolor == 'preferences':