Index: libs/iostreams/src/file_descriptor.cpp
===================================================================
--- libs/iostreams/src/file_descriptor.cpp	(revision 61787)
+++ libs/iostreams/src/file_descriptor.cpp	(working copy)
@@ -172,7 +172,7 @@
             oflag |= O_APPEND;
     }
     if (mode & BOOST_IOS::trunc)
-        oflag |= O_CREAT;
+        oflag |= O_TRUNC;
     #ifdef _LARGEFILE64_SOURCE
         oflag |= O_LARGEFILE;
     #endif