diff --git a/src/Makefile.dep b/src/Makefile.dep
index e9f83399..7b534b05 100644
--- a/src/Makefile.dep
+++ b/src/Makefile.dep
@@ -98,7 +98,7 @@ lj_crecord.o: lj_crecord.c lj_obj.h lua.h luaconf.h lj_def.h lj_arch.h \
  lj_cdata.h lj_cparse.h lj_cconv.h lj_carith.h lj_clib.h lj_ccall.h \
  lj_ff.h lj_ffdef.h lj_ir.h lj_jit.h lj_ircall.h lj_iropt.h lj_trace.h \
  lj_dispatch.h lj_traceerr.h lj_record.h lj_ffrecord.h lj_snap.h \
- lj_crecord.h lj_strfmt.h
+ lj_crecord.h lj_strfmt.h lj_strscan.h
 lj_ctype.o: lj_ctype.c lj_obj.h lua.h luaconf.h lj_def.h lj_arch.h \
  lj_gc.h lj_err.h lj_errmsg.h lj_str.h lj_tab.h lj_strfmt.h lj_ctype.h \
  lj_ccallback.h lj_buf.h
diff --git a/src/lj_crecord.c b/src/lj_crecord.c
index 79159454..e8ae426d 100644
--- a/src/lj_crecord.c
+++ b/src/lj_crecord.c
@@ -32,6 +32,7 @@
 #include "lj_crecord.h"
 #include "lj_dispatch.h"
 #include "lj_strfmt.h"
+#include "lj_strscan.h"
 
 /* Some local macros to save typing. Undef'd at the end. */
 #define IR(ref)			(&J->cur.ir[(ref)])
@@ -1807,11 +1808,21 @@ static CTypeID crec_bit64_type(CTState *cts, cTValue *tv)
   return 0;  /* Use regular 32 bit ops. */
 }
 
+static TRef crec_bit64_arg(jit_State *J, CType *d, TRef sp, TValue *sval)
+{
+  if (LJ_UNLIKELY(tref_isstr(sp))) {
+    if (lj_strscan_num(strV(sval), sval)) {
+      sp = emitir(IRTG(IR_STRTO, IRT_NUM), sp, 0);
+    }  /* else: interpreter will throw. */
+  }
+  return crec_ct_tv(J, d, 0, sp, sval);
+}
+
 void LJ_FASTCALL recff_bit64_tobit(jit_State *J, RecordFFData *rd)
 {
   CTState *cts = ctype_ctsG(J2G(J));
-  TRef tr = crec_ct_tv(J, ctype_get(cts, CTID_INT64), 0,
-		       J->base[0], &rd->argv[0]);
+  TRef tr = crec_bit64_arg(J, ctype_get(cts, CTID_INT64),
+			   J->base[0], &rd->argv[0]);
   if (!tref_isinteger(tr))
     tr = emitconv(tr, IRT_INT, tref_type(tr), 0);
   J->base[0] = tr;
@@ -1822,7 +1833,7 @@ int LJ_FASTCALL recff_bit64_unary(jit_State *J, RecordFFData *rd)
   CTState *cts = ctype_ctsG(J2G(J));
   CTypeID id = crec_bit64_type(cts, &rd->argv[0]);
   if (id) {
-    TRef tr = crec_ct_tv(J, ctype_get(cts, id), 0, J->base[0], &rd->argv[0]);
+    TRef tr = crec_bit64_arg(J, ctype_get(cts, id), J->base[0], &rd->argv[0]);
     tr = emitir(IRT(rd->data, id-CTID_INT64+IRT_I64), tr, 0);
     J->base[0] = emitir(IRTG(IR_CNEWI, IRT_CDATA), lj_ir_kint(J, id), tr);
     return 1;
@@ -1842,9 +1853,9 @@ int LJ_FASTCALL recff_bit64_nary(jit_State *J, RecordFFData *rd)
   if (id) {
     CType *ct = ctype_get(cts, id);
     uint32_t ot = IRT(rd->data, id-CTID_INT64+IRT_I64);
-    TRef tr = crec_ct_tv(J, ct, 0, J->base[0], &rd->argv[0]);
+    TRef tr = crec_bit64_arg(J, ct, J->base[0], &rd->argv[0]);
     for (i = 1; J->base[i] != 0; i++) {
-      TRef tr2 = crec_ct_tv(J, ct, 0, J->base[i], &rd->argv[i]);
+      TRef tr2 = crec_bit64_arg(J, ct, J->base[i], &rd->argv[i]);
       tr = emitir(ot, tr, tr2);
     }
     J->base[0] = emitir(IRTG(IR_CNEWI, IRT_CDATA), lj_ir_kint(J, id), tr);
@@ -1859,15 +1870,15 @@ int LJ_FASTCALL recff_bit64_shift(jit_State *J, RecordFFData *rd)
   CTypeID id;
   TRef tsh = 0;
   if (J->base[0] && tref_iscdata(J->base[1])) {
-    tsh = crec_ct_tv(J, ctype_get(cts, CTID_INT64), 0,
-		     J->base[1], &rd->argv[1]);
+    tsh = crec_bit64_arg(J, ctype_get(cts, CTID_INT64),
+			 J->base[1], &rd->argv[1]);
     if (!tref_isinteger(tsh))
       tsh = emitconv(tsh, IRT_INT, tref_type(tsh), 0);
     J->base[1] = tsh;
   }
   id = crec_bit64_type(cts, &rd->argv[0]);
   if (id) {
-    TRef tr = crec_ct_tv(J, ctype_get(cts, id), 0, J->base[0], &rd->argv[0]);
+    TRef tr = crec_bit64_arg(J, ctype_get(cts, id), J->base[0], &rd->argv[0]);
     uint32_t op = rd->data;
     if (!tsh) tsh = lj_opt_narrow_tobit(J, J->base[1]);
     if (!(op < IR_BROL ? LJ_TARGET_MASKSHIFT : LJ_TARGET_MASKROT) &&
@@ -1897,7 +1908,7 @@ TRef recff_bit64_tohex(jit_State *J, RecordFFData *rd, TRef hdr)
     CTypeID id2 = 0;
     n = (int32_t)lj_carith_check64(J->L, 2, &id2);
     if (id2)
-      trsf = crec_ct_tv(J, ctype_get(cts, CTID_INT32), 0, trsf, &rd->argv[1]);
+      trsf = crec_bit64_arg(J, ctype_get(cts, CTID_INT32), trsf, &rd->argv[1]);
     else
       trsf = lj_opt_narrow_tobit(J, trsf);
     emitir(IRTGI(IR_EQ), trsf, lj_ir_kint(J, n));  /* Specialize to n. */
@@ -1908,7 +1919,7 @@ TRef recff_bit64_tohex(jit_State *J, RecordFFData *rd, TRef hdr)
   if ((uint32_t)n > 254) n = 254;
   sf |= ((SFormat)((n+1)&255) << STRFMT_SH_PREC);
   if (id) {
-    tr = crec_ct_tv(J, ctype_get(cts, id), 0, J->base[0], &rd->argv[0]);
+    tr = crec_bit64_arg(J, ctype_get(cts, id), J->base[0], &rd->argv[0]);
     if (n < 16)
       tr = emitir(IRT(IR_BAND, IRT_U64), tr,
 		  lj_ir_kint64(J, ((uint64_t)1 << 4*n)-1));