diff --git a/xen/arch/x86/cpu/mcheck/mce-apei.c b/xen/arch/x86/cpu/mcheck/mce-apei.c
index 53b6735896..b895020882 100644
--- a/xen/arch/x86/cpu/mcheck/mce-apei.c
+++ b/xen/arch/x86/cpu/mcheck/mce-apei.c
@@ -37,10 +37,10 @@
 #include "mce.h"
 
 #define CPER_CREATOR_MCE						\
-	UUID_LE(0x75a574e3, 0x5052, 0x4b29, 0x8a, 0x8e, 0xbe, 0x2c,	\
+	UUID_LE(0x75a574e3U, 0x5052, 0x4b29, 0x8a, 0x8e, 0xbe, 0x2c,	\
 		0x64, 0x90, 0xb8, 0x9d)
 #define CPER_SECTION_TYPE_MCE						\
-	UUID_LE(0xfe08ffbe, 0x95e4, 0x4be7, 0xbc, 0x73, 0x40, 0x96,	\
+	UUID_LE(0xfe08ffbeU, 0x95e4, 0x4be7, 0xbc, 0x73, 0x40, 0x96,	\
 		0x04, 0x4a, 0x38, 0xfc)
 
 /*