diff --git a/llvm/lib/Support/SourceMgr.cpp b/llvm/lib/Support/SourceMgr.cpp
index 595c6ee..003cb56 100644
--- a/llvm/lib/Support/SourceMgr.cpp
+++ b/llvm/lib/Support/SourceMgr.cpp
@@ -49,9 +49,9 @@
   }
 }
 
-size_t SourceMgr::AddIncludeFile(const std::string &Filename,
-                                 SMLoc IncludeLoc,
-                                 std::string &IncludedFile) {
+unsigned SourceMgr::AddIncludeFile(const std::string &Filename,
+                                   SMLoc IncludeLoc,
+                                   std::string &IncludedFile) {
   IncludedFile = Filename;
   ErrorOr<std::unique_ptr<MemoryBuffer>> NewBufOrErr =
       MemoryBuffer::getFile(IncludedFile.c_str());