diff --git a/mercurial/templater.py b/mercurial/templater.py
--- a/mercurial/templater.py
+++ b/mercurial/templater.py
@@ -539,7 +539,12 @@ def word(context, mapping, args):
         raise error.ParseError(_("word expects two or three arguments, got %d")
                                % len(args))
 
-    num = int(stringify(args[0][0](context, mapping, args[0][1])))
+    try:
+        num = int(stringify(args[0][0](context, mapping, args[0][1])))
+    except ValueError:
+        # i18n: "word" is a keyword
+        raise error.ParseError(
+                _("Use strings like '3' for numbers passed to word function"))
     text = stringify(args[1][0](context, mapping, args[1][1]))
     if len(args) == 3:
         splitter = stringify(args[2][0](context, mapping, args[2][1]))
diff --git a/tests/test-command-template.t b/tests/test-command-template.t
--- a/tests/test-command-template.t
+++ b/tests/test-command-template.t
@@ -2620,3 +2620,9 @@ Test word error messages for not enough 
   $ hg log -Gv -R a --template "{word('0', desc, 'o', 'h', 'b', 'o', 'y')}"
   hg: parse error: word expects two or three arguments, got 7
   [255]
+
+Test word for invalid numbers
+
+  $ hg log -Gv -R a --template "{word(2, desc)}"
+  hg: parse error: Use strings like '3' for numbers passed to word function
+  [255]