diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
index 51c6661aca77..0cbc71b7af50 100644
--- a/tools/testing/selftests/kvm/include/x86_64/processor.h
+++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
@@ -786,7 +786,7 @@ void vm_install_exception_handler(struct kvm_vm *vm, int vector,
 	"lea 1f(%%rip), %%r10\n\t"				\
 	"lea 2f(%%rip), %%r11\n\t"				\
 	"1: " insn "\n\t"					\
-	"mov $0, %[vector]\n\t"					\
+	"movb $0, %[vector]\n\t"				\
 	"jmp 3f\n\t"						\
 	"2:\n\t"						\
 	"mov  %%r9b, %[vector]\n\t"				\