diff --git a/SecurityPkg/VariableAuthenticated/RuntimeDxe/Variable.c b/SecurityPkg/VariableAuthenticated/RuntimeDxe/Variable.c
index ac043d9a17..04b992d5bf 100644
--- a/SecurityPkg/VariableAuthenticated/RuntimeDxe/Variable.c
+++ b/SecurityPkg/VariableAuthenticated/RuntimeDxe/Variable.c
@@ -3883,8 +3883,9 @@ GetFvbInfoByAddress (
   UINTN                                   Index;
   EFI_PHYSICAL_ADDRESS                    FvbBaseAddress;
   EFI_FIRMWARE_VOLUME_BLOCK_PROTOCOL      *Fvb;
-  EFI_FIRMWARE_VOLUME_HEADER              *FwVolHeader;
   EFI_FVB_ATTRIBUTES_2                    Attributes;
+  UINTN                                   BlockSize;
+  UINTN                                   NumberOfBlocks;
 
   HandleBuffer = NULL;
   //
@@ -3922,8 +3923,15 @@ GetFvbInfoByAddress (
       continue;
     }
 
-    FwVolHeader = (EFI_FIRMWARE_VOLUME_HEADER *) ((UINTN) FvbBaseAddress);
-    if ((Address >= FvbBaseAddress) && (Address < (FvbBaseAddress + FwVolHeader->FvLength))) {
+    //
+    // Assume one FVB has one type of BlockSize.
+    //
+    Status = Fvb->GetBlockSize (Fvb, 0, &BlockSize, &NumberOfBlocks);
+    if (EFI_ERROR (Status)) {
+      continue;
+    }
+
+    if ((Address >= FvbBaseAddress) && (Address < (FvbBaseAddress + BlockSize * NumberOfBlocks))) {
       if (FvbHandle != NULL) {
         *FvbHandle  = HandleBuffer[Index];
       }