diff --git a/lib/Bytecode/Archive/ArchiveWriter.cpp b/lib/Bytecode/Archive/ArchiveWriter.cpp
index a5b52f4..c99d851 100644
--- a/lib/Bytecode/Archive/ArchiveWriter.cpp
+++ b/lib/Bytecode/Archive/ArchiveWriter.cpp
@@ -209,7 +209,7 @@
     mFile = new sys::MappedFile();
     if (mFile->open(member.getPath(), sys::MappedFile::READ_ACCESS, &ErrMsg))
       throw ErrMsg;
-    if (data = (const char*) mFile->map(&ErrMsg))
+    if (!(data = (const char*) mFile->map(&ErrMsg)))
       throw ErrMsg;
     fSize = mFile->size();
   }