diff --git a/UefiCpuPkg/Library/MtrrLib/MtrrLib.c b/UefiCpuPkg/Library/MtrrLib/MtrrLib.c
index 8e8427291f..c38191a7ef 100644
--- a/UefiCpuPkg/Library/MtrrLib/MtrrLib.c
+++ b/UefiCpuPkg/Library/MtrrLib/MtrrLib.c
@@ -702,6 +702,7 @@ MtrrLibGetPositiveMtrrNumber (
   BOOLEAN        UseLeastAlignment;
 
   UseLeastAlignment = TRUE;
+  SubLength = 0;
 
   //
   // Calculate the alignment of the base address.
@@ -854,6 +855,7 @@ MtrrLibGetMtrrNumber (
   *SubLeft = 0;
   *SubRight = 0;
   LeastSubtractiveMtrrNumber = 0;
+  BaseAlignment = 0;
 
   //
   // Get the optimal left subtraction solution.
@@ -1627,6 +1629,8 @@ MtrrLibSetMemoryAttributeInVariableMtrr (
   UINT32                    SubtractiveRight;
   BOOLEAN                   UseLeastAlignment;
 
+  Alignment = 0;
+
   MtrrNumber = MtrrLibGetMtrrNumber (Ranges, RangeCount, VariableMtrr, *VariableMtrrCount,
                                      BaseAddress, Length, Type, Alignment0, &SubtractiveLeft, &SubtractiveRight);