diff --git a/xen/arch/x86/hvm/viridian/viridian.c b/xen/arch/x86/hvm/viridian/viridian.c
index 7405c117bc..61171e3363 100644
--- a/xen/arch/x86/hvm/viridian/viridian.c
+++ b/xen/arch/x86/hvm/viridian/viridian.c
@@ -291,7 +291,7 @@ static void enable_hypercall_page(struct domain *d)
      * calling convention) to differentiate Xen and Viridian hypercalls.
      */
     *(u8  *)(p + 0) = 0x0d; /* orl $0x80000000, %eax */
-    *(u32 *)(p + 1) = 0x80000000;
+    *(u32 *)(p + 1) = 0x80000000U;
     *(u8  *)(p + 5) = 0x0f; /* vmcall/vmmcall */
     *(u8  *)(p + 6) = 0x01;
     *(u8  *)(p + 7) = (cpu_has_vmx ? 0xc1 : 0xd9);
diff --git a/xen/arch/x86/include/asm/guest/hyperv-tlfs.h b/xen/arch/x86/include/asm/guest/hyperv-tlfs.h
index 38f997a0c8..a6915ad731 100644
--- a/xen/arch/x86/include/asm/guest/hyperv-tlfs.h
+++ b/xen/arch/x86/include/asm/guest/hyperv-tlfs.h
@@ -471,30 +471,30 @@ typedef struct _HV_REFERENCE_TSC_PAGE {
 
 /* Define hypervisor message types. */
 enum hv_message_type {
-	HVMSG_NONE			= 0x00000000,
+	HVMSG_NONE			= 0x00000000U,
 
 	/* Memory access messages. */
-	HVMSG_UNMAPPED_GPA		= 0x80000000,
-	HVMSG_GPA_INTERCEPT		= 0x80000001,
+	HVMSG_UNMAPPED_GPA		= 0x80000000U,
+	HVMSG_GPA_INTERCEPT		= 0x80000001U,
 
 	/* Timer notification messages. */
-	HVMSG_TIMER_EXPIRED			= 0x80000010,
+	HVMSG_TIMER_EXPIRED			= 0x80000010U,
 
 	/* Error messages. */
-	HVMSG_INVALID_VP_REGISTER_VALUE	= 0x80000020,
-	HVMSG_UNRECOVERABLE_EXCEPTION	= 0x80000021,
-	HVMSG_UNSUPPORTED_FEATURE		= 0x80000022,
+	HVMSG_INVALID_VP_REGISTER_VALUE	= 0x80000020U,
+	HVMSG_UNRECOVERABLE_EXCEPTION	= 0x80000021U,
+	HVMSG_UNSUPPORTED_FEATURE		= 0x80000022U,
 
 	/* Trace buffer complete messages. */
-	HVMSG_EVENTLOG_BUFFERCOMPLETE	= 0x80000040,
+	HVMSG_EVENTLOG_BUFFERCOMPLETE	= 0x80000040U,
 
 	/* Platform-specific processor intercept messages. */
-	HVMSG_X64_IOPORT_INTERCEPT		= 0x80010000,
-	HVMSG_X64_MSR_INTERCEPT		= 0x80010001,
-	HVMSG_X64_CPUID_INTERCEPT		= 0x80010002,
-	HVMSG_X64_EXCEPTION_INTERCEPT	= 0x80010003,
-	HVMSG_X64_APIC_EOI			= 0x80010004,
-	HVMSG_X64_LEGACY_FP_ERROR		= 0x80010005
+	HVMSG_X64_IOPORT_INTERCEPT		= 0x80010000U,
+	HVMSG_X64_MSR_INTERCEPT		= 0x80010001U,
+	HVMSG_X64_CPUID_INTERCEPT		= 0x80010002U,
+	HVMSG_X64_EXCEPTION_INTERCEPT	= 0x80010003U,
+	HVMSG_X64_APIC_EOI			= 0x80010004U,
+	HVMSG_X64_LEGACY_FP_ERROR		= 0x80010005U
 };
 
 /* Define synthetic interrupt controller message flags. */