diff --git a/BaseTools/Source/C/Common/Decompress.c b/BaseTools/Source/C/Common/Decompress.c
index 4b83e88210..b2049bd01c 100644
--- a/BaseTools/Source/C/Common/Decompress.c
+++ b/BaseTools/Source/C/Common/Decompress.c
@@ -89,11 +89,11 @@ Returns: (VOID)
 
 --*/
 {
-  Sd->mBitBuf = (UINT32) (Sd->mBitBuf << NumOfBits);
+  Sd->mBitBuf = (UINT32) (((UINT64)Sd->mBitBuf) << NumOfBits);
 
   while (NumOfBits > Sd->mBitCount) {
 
-    Sd->mBitBuf |= (UINT32) (Sd->mSubBitBuf << (NumOfBits = (UINT16) (NumOfBits - Sd->mBitCount)));
+    Sd->mBitBuf |= (UINT32) (((UINT64)Sd->mSubBitBuf) << (NumOfBits = (UINT16) (NumOfBits - Sd->mBitCount)));
 
     if (Sd->mCompSize > 0) {
       //
diff --git a/BaseTools/Source/C/TianoCompress/TianoCompress.c b/BaseTools/Source/C/TianoCompress/TianoCompress.c
index f810511f5f..046fb36a17 100644
--- a/BaseTools/Source/C/TianoCompress/TianoCompress.c
+++ b/BaseTools/Source/C/TianoCompress/TianoCompress.c
@@ -2066,11 +2066,11 @@ Returns: (VOID)
 
 --*/
 {
-  Sd->mBitBuf = (UINT32) (Sd->mBitBuf << NumOfBits);
+  Sd->mBitBuf = (UINT32) (((UINT64)Sd->mBitBuf) << NumOfBits);
 
   while (NumOfBits > Sd->mBitCount) {
 
-    Sd->mBitBuf |= (UINT32) (Sd->mSubBitBuf << (NumOfBits = (UINT16) (NumOfBits - Sd->mBitCount)));
+    Sd->mBitBuf |= (UINT32) (((UINT64)Sd->mSubBitBuf) << (NumOfBits = (UINT16) (NumOfBits - Sd->mBitCount)));
 
     if (Sd->mCompSize > 0) {
       //