diff --git a/lib/Basic/SourceManager.cpp b/lib/Basic/SourceManager.cpp
index 73ac2ab..1141bed 100644
--- a/lib/Basic/SourceManager.cpp
+++ b/lib/Basic/SourceManager.cpp
@@ -51,7 +51,7 @@
 #endif
   
   // If the file is larger than some threshold, use 'read', otherwise use mmap.
-  if (FileEnt->getSize() >= 4096*4)
+  if (FileEnt->getSize() >= 4096*12)
     return MemoryBuffer::getFile(FileEnt->getName(), strlen(FileEnt->getName()),
                                  0, FileEnt->getSize());