diff --git a/src/I18n.php b/src/I18n.php
index d607487..72a5c17 100644
--- a/src/I18n.php
+++ b/src/I18n.php
@@ -491,7 +491,7 @@ class I18n {
     $result = run_external_command(array_merge(
       array(
         'msgcat',
-        "-t", "utf-8", "--use-first",
+        "-t", "utf-8", "--use-first", "--force-po",
         "-o", "$root_path/messages.pot",
         "$root_path/headers.pot",
       ),