diff --git a/OvmfPkg/OvmfXen.dsc b/OvmfPkg/OvmfXen.dsc
index 22970eda5d..477d8c76a1 100644
--- a/OvmfPkg/OvmfXen.dsc
+++ b/OvmfPkg/OvmfXen.dsc
@@ -439,6 +439,9 @@
   # Point to the MdeModulePkg/Application/UiApp/UiApp.inf
   gEfiMdeModulePkgTokenSpaceGuid.PcdBootManagerMenuFile|{ 0x21, 0xaa, 0x2c, 0x46, 0x14, 0x76, 0x03, 0x45, 0x83, 0x6e, 0x8a, 0xb6, 0xf4, 0x66, 0x23, 0x31 }
 
+  ## Xen vlapic's frequence is 100 MHz
+  gEfiMdePkgTokenSpaceGuid.PcdFSBClock|100000000
+
 ################################################################################
 #
 # Pcd Dynamic Section - list of all EDK II PCD Entries defined by this Platform