diff --git a/src/lj_asm_x86.h b/src/lj_asm_x86.h
index dcdc727a..35f48727 100644
--- a/src/lj_asm_x86.h
+++ b/src/lj_asm_x86.h
@@ -2970,6 +2970,7 @@ static Reg asm_setup_call_slots(ASMState *as, IRIns *ir, const CCallInfo *ci)
 static void asm_setup_target(ASMState *as)
 {
   asm_exitstub_setup(as, as->T->nsnap);
+  as->mrm.base = 0;
 }
 
 /* -- Trace patching ------------------------------------------------------ */
diff --git a/src/lj_ir.c b/src/lj_ir.c
index 0a206ebb..87fd0f4d 100644
--- a/src/lj_ir.c
+++ b/src/lj_ir.c
@@ -224,6 +224,7 @@ TRef lj_ir_k64(jit_State *J, IROp op, uint64_t u64)
   ir[1].tv.u64 = u64;
   ir->t.irt = t;
   ir->o = op;
+  ir->op12 = 0;
   ir->prev = J->chain[op];
   J->chain[op] = (IRRef1)ref;
 found:
@@ -281,6 +282,7 @@ TRef lj_ir_kgc(jit_State *J, GCobj *o, IRType t)
   ref = ir_nextkgc(J);
   ir = IR(ref);
   /* NOBARRIER: Current trace is a GC root. */
+  ir->op12 = 0;
   setgcref(ir[LJ_GC64].gcr, o);
   ir->t.irt = (uint8_t)t;
   ir->o = IR_KGC;
@@ -298,6 +300,7 @@ TRef lj_ir_ktrace(jit_State *J)
   lua_assert(irt_toitype_(IRT_P64) == LJ_TTRACE);
   ir->t.irt = IRT_P64;
   ir->o = LJ_GC64 ? IR_KNUM : IR_KNULL;  /* Not IR_KGC yet, but same size. */
+  ir->op12 = 0;
   ir->prev = 0;
   return TREF(ref, IRT_P64);
 }
@@ -319,6 +322,7 @@ TRef lj_ir_kptr_(jit_State *J, IROp op, void *ptr)
   ref = ir_nextk(J);
 #endif
   ir = IR(ref);
+  ir->op12 = 0;
   setmref(ir[LJ_GC64].ptr, ptr);
   ir->t.irt = IRT_PGC;
   ir->o = op;