index() applied BM optimization to wrong argument

p4raw-id: //depot/perl@1779

1 files changed, 2 insertions, 1 deletions

diff --git a/util.c b/util.c
index e079d420a0..5be4969e75 100644
--- a/util.c
+++ b/util.c
@@ -900,10 +900,11 @@ fbm_compile(SV *sv, U32 flags /* not used yet */)
     register unsigned char *s;
     register unsigned char *table;
     register U32 i;
-    register U32 len = SvCUR(sv);
+    STRLEN len;
     I32 rarest = 0;
     U32 frequency = 256;
 
+    s = SvPV_force(sv, len);
     sv_upgrade(sv, SVt_PVBM);
     if (len > 255 || len == 0)	/* TAIL might be on on a zero-length string. */
 	return;			/* can't have offsets that big */