diff --git a/drivers/bios_emulator/x86emu/ops2.c b/drivers/bios_emulator/x86emu/ops2.c
index 1ff27b2af95..29a166f7fe9 100644
--- a/drivers/bios_emulator/x86emu/ops2.c
+++ b/drivers/bios_emulator/x86emu/ops2.c
@@ -66,7 +66,7 @@ void x86emuOp2_illegal_op(
     END_OF_INSTR();
 }
 
-#define xorl(a,b)   ((a) && !(b)) || (!(a) && (b))
+#define xorl(a, b)   (((a) && !(b)) || (!(a) && (b)))
 
 /****************************************************************************
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