diff --git a/UefiCpuPkg/Library/RegisterCpuFeaturesLib/RegisterCpuFeaturesLib.c b/UefiCpuPkg/Library/RegisterCpuFeaturesLib/RegisterCpuFeaturesLib.c
index 7bb9240402..60daa5cc87 100644
--- a/UefiCpuPkg/Library/RegisterCpuFeaturesLib/RegisterCpuFeaturesLib.c
+++ b/UefiCpuPkg/Library/RegisterCpuFeaturesLib/RegisterCpuFeaturesLib.c
@@ -957,6 +957,7 @@ GetAcpiCpuData (
     //
     // Allocate buffer for empty RegisterTable and PreSmmInitRegisterTable for all CPUs
     //
+    NumberOfCpus = AcpiCpuData->NumberOfCpus;
     TableSize = 2 * NumberOfCpus * sizeof (CPU_REGISTER_TABLE);
     RegisterTable  = AllocatePages (EFI_SIZE_TO_PAGES (TableSize));
     ASSERT (RegisterTable != NULL);