diff --git a/src/po/Make_all.mak b/src/po/Make_all.mak
index 7a6144e..f5f8e13 100644
--- a/src/po/Make_all.mak
+++ b/src/po/Make_all.mak
@@ -188,3 +188,5 @@
 	optwin.js \
 	defaults.js
 
+# Arguments for xgettext to pick up messages to translate from the source code.
+XGETTEXT_KEYWORDS = --keyword=_ --keyword=N_ --keyword=NGETTEXT:1,2 --keyword=PLURAL_MSG:2,4