Index: src/runtime/lookup-asm/lookup-asm-x86-win32.S
==================================================================
--- src/runtime/lookup-asm/lookup-asm-x86-win32.S
+++ src/runtime/lookup-asm/lookup-asm-x86-win32.S
@@ -29,10 +29,13 @@
 \name:
 	mov	edx, [esp+4]
 	test	edx, edx
 	jz	short ret_nil
 
+	bt	edx, 0
+	jc	short .Ltagged_pointer_\name
+
 	mov	edx, [edx]
 	mov	edx, [edx+32]
 
 .Lmain_\name:
 	mov	eax, [esp+8]
@@ -45,16 +48,23 @@
 	mov	edx, [edx+ecx*4]
 	movzx	ecx, byte ptr [eax]
 	mov	eax, [edx+ecx*4]
 
 	test	eax, eax
-	jz	short 0f
+	jz	\not_found
 
 	ret
 
-0:
-	jmp	\not_found
+.Ltagged_pointer_\name:
+	movzx	edx, dl
+	shr	edx, 1
+
+	mov	eax, offset _objc_tagged_pointer_classes
+	mov	edx, [eax+edx*4]
+	mov	edx, [edx+32]
+
+	jmp	short .Lmain_\name
 .endm
 
 .macro generate_lookup_super name lookup
 \name:
 	mov	edx, [esp+4]