diff --git a/src/libmach/hexify.c b/src/libmach/hexify.c
new file mode 100644
index 0000000..5f3ed50
--- /dev/null
+++ b/src/libmach/hexify.c
@@ -0,0 +1,20 @@
+#include <u.h>
+#include <libc.h>
+#include <bio.h>
+#include <mach.h>
+
+char *
+_hexify(char *buf, ulong p, int zeros)
+{
+	ulong d;
+
+	d = p/16;
+	if(d)
+		buf = _hexify(buf, d, zeros-1);
+	else
+		while(zeros--)
+			*buf++ = '0';
+	*buf++ = "0123456789abcdef"[p&0x0f];
+	return buf;
+}
+