diff --git a/lib/Makefile.am b/lib/Makefile.am
index 603887e34..8638d6f1c 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -126,7 +126,7 @@ EXTRA_DIST += stdbool_.h
 MOSTLYCLEANFILES += stdbool.h stdbool.ht
 # Create stdbool.h on systems that lack a working one.
 stdbool.h: stdbool_.h
-	sed -e 's/@''HAVE__BOOL''@/$(HAVE__BOOL)/g' $(srcdir)/stdbool_.h > $@t
+	cp $(srcdir)/stdbool_.h $@-t
 	mv $@t $@
 
 BUILT_SOURCES += $(ALLOCA_H)