diff --git a/reactos/lib/sdk/crt/math/i386/ci.c b/reactos/lib/sdk/crt/math/i386/ci.c
index ea0fb3663ac..1b216495df9 100644
--- a/reactos/lib/sdk/crt/math/i386/ci.c
+++ b/reactos/lib/sdk/crt/math/i386/ci.c
@@ -61,7 +61,7 @@ double	CDECL	_CIatan(void)
  */
 double	CDECL	_CIatan2(void)
 {
-	FPU_DOUBLES(x, y);
+	FPU_DOUBLES(y, x);
 	return atan2(y, x);
 }
 /*