diff --git a/xen/arch/x86/time.c b/xen/arch/x86/time.c
index 092a3d2f73..d978c8170e 100644
--- a/xen/arch/x86/time.c
+++ b/xen/arch/x86/time.c
@@ -103,7 +103,7 @@ static inline u32 mul_frac(u32 multiplicand, u32 multiplier)
 static inline u64 scale_delta(u64 delta, struct time_scale *scale)
 {
     u64 product;
-#ifdef CONFIG_x86_32
+#ifdef CONFIG_X86_32
     u32 tmp1, tmp2;
 #endif