Index: src/mongo/watchdog/watchdog.cpp
--- src/mongo/watchdog/watchdog.cpp.orig
+++ src/mongo/watchdog/watchdog.cpp
@@ -576,7 +576,7 @@ void checkFile(OperationContext* opCtx, const boost::f
     std::string nowStr = now.toString();
 
 // Apple does not support O_DIRECT, so instead we use fcntl to enable the F_NOCACHE flag later.
-#if defined(__APPLE__)
+#if defined(__APPLE__) || defined(__OpenBSD__)
     int fd = open(file.generic_string().c_str(), O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
 #else
     int fd = open(file.generic_string().c_str(), O_RDWR | O_CREAT | O_DIRECT, S_IRUSR | S_IWUSR);
