$OpenBSD$
--- src/zm_thread.cpp.orig	Wed Feb  3 19:30:55 2016
+++ src/zm_thread.cpp	Sat Apr  9 10:50:45 2016
@@ -234,7 +234,11 @@ template <class T> void ThreadData<T>::updateValueBroa
 
 Thread::Thread() :
     mThreadCondition( mThreadMutex ),
+#ifdef __OpenBSD__
+    mPid( NULL ),
+#else
     mPid( -1 ),
+#endif
     mStarted( false ),
     mRunning( false )
 {
