diff --git a/MdeModulePkg/Application/CapsuleApp/CapsuleDump.c b/MdeModulePkg/Application/CapsuleApp/CapsuleDump.c
index 97f1893ef4..4c85e8c23d 100644
--- a/MdeModulePkg/Application/CapsuleApp/CapsuleDump.c
+++ b/MdeModulePkg/Application/CapsuleApp/CapsuleDump.c
@@ -214,7 +214,7 @@ IsNestedFmpCapsule (
   // FMP GUID after ESRT one
   //
   NestedCapsuleHeader = (EFI_CAPSULE_HEADER *)((UINT8 *)CapsuleHeader + CapsuleHeader->HeaderSize);
-  NestedCapsuleSize = (UINTN)CapsuleHeader + CapsuleHeader->HeaderSize - (UINTN)NestedCapsuleHeader;
+  NestedCapsuleSize = (UINTN)CapsuleHeader + CapsuleHeader->CapsuleImageSize- (UINTN)NestedCapsuleHeader;
   if (NestedCapsuleSize < sizeof(EFI_CAPSULE_HEADER)) {
     return FALSE;
   }