diff --git a/llvm/tools/llvm-lipo/llvm-lipo.cpp b/llvm/tools/llvm-lipo/llvm-lipo.cpp
index ba413b10fb09..a063fcec7574 100644
--- a/llvm/tools/llvm-lipo/llvm-lipo.cpp
+++ b/llvm/tools/llvm-lipo/llvm-lipo.cpp
@@ -688,7 +688,8 @@ static void createUniversalBinary(SmallVectorImpl<Slice> &Slices,
     return sys::fs::can_execute(S.getBinary()->getFileName());
   });
   const uint64_t OutputFileSize =
-      FatArchList.back().offset + FatArchList.back().size;
+      static_cast<uint64_t>(FatArchList.back().offset) +
+      FatArchList.back().size;
   Expected<std::unique_ptr<FileOutputBuffer>> OutFileOrError =
       FileOutputBuffer::create(OutputFileName, OutputFileSize,
                                IsExecutable ? FileOutputBuffer::F_executable