diff --git a/insns.def b/insns.def
index 8716ea93e..696354d63 100644
--- a/insns.def
+++ b/insns.def
@@ -1320,7 +1320,7 @@ setinlinecache
 {
     IC ic = GET_CONST_INLINE_CACHE(dst);
 
-    ic->ic_value = val;
+    GC_WB(&ic->ic_value, val);
     ic->ic_vmstat = GET_VM_STATE_VERSION();
 }
 
diff --git a/iseq.c b/iseq.c
index 78793cb12..477ad21e6 100644
--- a/iseq.c
+++ b/iseq.c
@@ -113,18 +113,18 @@ set_relation(rb_iseq_t *iseq, const VALUE parent)
     /* set class nest stack */
     if (type == ISEQ_TYPE_TOP) {
 	/* toplevel is private */
-	iseq->cref_stack = NEW_BLOCK(th->top_wrapper ? th->top_wrapper : rb_cObject);
+	GC_WB(&iseq->cref_stack, NEW_BLOCK(th->top_wrapper ? th->top_wrapper : rb_cObject));
 	iseq->cref_stack->nd_file = 0;
 	iseq->cref_stack->nd_visi = NOEX_PRIVATE;
     }
     else if (type == ISEQ_TYPE_METHOD || type == ISEQ_TYPE_CLASS) {
-	iseq->cref_stack = NEW_BLOCK(0); /* place holder */
+	GC_WB(&iseq->cref_stack, NEW_BLOCK(0)); /* place holder */
 	iseq->cref_stack->nd_file = 0;
     }
     else if (RTEST(parent)) {
 	rb_iseq_t *piseq;
 	GetISeqPtr(parent, piseq);
-	iseq->cref_stack = piseq->cref_stack;
+	GC_WB(&iseq->cref_stack, piseq->cref_stack);
     }
 
     if (type == ISEQ_TYPE_TOP ||