diff --git a/test/MC/X86/x86_nop.s b/test/MC/X86/x86_nop.s
index 37dec252b72..de0fc088344 100644
--- a/test/MC/X86/x86_nop.s
+++ b/test/MC/X86/x86_nop.s
@@ -1,4 +1,4 @@
-# RUN: llvm-mc -filetype=obj -mcpu=geode %s -o %t
+# RUN: llvm-mc -filetype=obj -arch=x86 -mcpu=geode %s -o %t
 # RUN: llvm-objdump -disassemble %t | FileCheck %s
 
 # CHECK-NOT: nopw