diff --git a/m4/Makefile.am.in b/m4/Makefile.am.in
index aef33f597..c7682ad88 100644
--- a/m4/Makefile.am.in
+++ b/m4/Makefile.am.in
@@ -12,4 +12,5 @@ Makefile.am: Makefile.am.in
 	    |sed 's/@$$/%/;s/@/ \\@/g' |tr @% '\012\012' \
 	  >> $@t
 	sed -n '/^##m4-files-end/,$$p' $< >> $@t
+	chmod a-w $@t
 	mv $@t $@