diff --git a/tools/patch-header.janet b/tools/patch-header.janet
index af44aba0..96ed0b5e 100644
--- a/tools/patch-header.janet
+++ b/tools/patch-header.janet
@@ -1,3 +1,3 @@
 # Patch janet.h 
 (def [_ janeth janetconf output] (dyn :args))
-(spit output (peg/replace `#include "janetconf.h"` (slurp janetconf) (slurp janeth)))
+(spit output (string/replace `#include "janetconf.h"` (slurp janetconf) (slurp janeth)))