diff --git a/core/iwasm/interpreter/wasm_loader.c b/core/iwasm/interpreter/wasm_loader.c
index c8b4e6b7d9..39ea523ccc 100644
--- a/core/iwasm/interpreter/wasm_loader.c
+++ b/core/iwasm/interpreter/wasm_loader.c
@@ -830,32 +830,49 @@ load_init_expr(WASMModule *module, const uint8 **p_buf, const uint8 *buf_end,
             case INIT_EXPR_TYPE_REFNULL_CONST:
             {
                 uint8 type1;
-
-#if WASM_ENABLE_GC == 0
+#if WASM_ENABLE_GC != 0
+                const uint8 *p_copy = p;
+                int32 heap_type;
+                read_leb_int32(p_copy, p_end, heap_type);
+#endif
                 CHECK_BUF(p, p_end, 1);
                 type1 = read_uint8(p);
 
+#if WASM_ENABLE_GC == 0
                 cur_value.ref_index = NULL_REF;
                 if (!push_const_expr_stack(&const_expr_ctx, flag, type1,
                                            &cur_value, error_buf,
                                            error_buf_size))
                     goto fail;
 #else
-                int32 heap_type;
-                read_leb_int32(p, p_end, heap_type);
-                type1 = (uint8)((int32)0x80 + heap_type);
-
                 cur_value.gc_obj = NULL_REF;
 
+                /*
+                 * According to the current GC SPEC rules, the heap_type must be
+                 * validated when ref.null is used. It can be an absheaptype,
+                 * or the type C.types[typeidx] must be defined in the context.
+                 */
+                if (heap_type >= 0) {
+                    if (!check_type_index(module, module->type_count, heap_type,
+                                          error_buf, error_buf_size)) {
+                        goto fail;
+                    }
+                }
+                else {
+                    if (!wasm_is_valid_heap_type(heap_type)) {
+                        set_error_buf_v(error_buf, error_buf_size,
+                                        "unknown type %d", heap_type);
+                        goto fail;
+                    }
+                }
+
                 if (!is_byte_a_type(type1)
-                    || !wasm_is_valid_heap_type(heap_type)
                     || wasm_is_type_multi_byte_type(type1)) {
                     p--;
                     read_leb_uint32(p, p_end, type_idx);
                     if (!check_type_index(module, module->type_count, type_idx,
                                           error_buf, error_buf_size))
                         goto fail;
-
                     wasm_set_refheaptype_typeidx(&cur_ref_type.ref_ht_typeidx,
                                                  true, type_idx);
                     if (!push_const_expr_stack(&const_expr_ctx, flag,