diff --git a/src/runtime/metal/metal_device_api.mm b/src/runtime/metal/metal_device_api.mm
index c0fe0b76a04e..f7c2976d2240 100644
--- a/src/runtime/metal/metal_device_api.mm
+++ b/src/runtime/metal/metal_device_api.mm
@@ -55,8 +55,14 @@
         break;
       }
       case kWarpSize: {
-        // Set warp size to be 1 for safty reason.
+#if defined(__x86_64__)
         *rv = 1;
+#elif defined(__aarch64__)
+        *rv = 32;
+#else
+        LOG(WARNING) << "The CPU architecture is neither x86 nor aarch64. Fallback to warp size 1.";
+        *rv = 1;
+#endif
         break;
       }
       case kMaxSharedMemoryPerBlock: