$OpenBSD: patch-mono_utils_mono-threads-openbsd_c,v 1.2 2018/01/02 13:19:10 robert Exp $
Index: mono/utils/mono-threads-openbsd.c
--- mono/utils/mono-threads-openbsd.c.orig
+++ mono/utils/mono-threads-openbsd.c
@@ -6,6 +6,7 @@
 
 #if defined(__OpenBSD__)
 
+#include <mono/utils/mono-threads.h>
 #include <pthread.h>
 #include <pthread_np.h>
 
