diff --git a/include/stdex/stream.hpp b/include/stdex/stream.hpp
index 8b8c4de67..4bc3c2438 100644
--- a/include/stdex/stream.hpp
+++ b/include/stdex/stream.hpp
@@ -2811,6 +2811,8 @@ namespace stdex
 				case mode_create: flags |= O_CREAT | O_TRUNC; break;
 				default: throw std::invalid_argument("invalid mode");
 				}
+				if (mode & share_reading) flags |= O_SHLOCK;
+				if (mode & share_writing) flags |= O_EXLOCK;
 				if (mode & hint_write_thru) flags |= O_DSYNC;
 #ifndef __APPLE__
 				if (mode & hint_no_buffering) flags |= O_RSYNC;