--- flow/ThreadPrimitives.h.orig	2018-08-01 01:25:10 UTC
+++ flow/ThreadPrimitives.h
@@ -25,7 +25,7 @@
 #include "Error.h"
 #include "Trace.h"
 
-#ifdef __linux__
+#if defined(__linux__) || defined(__FreeBSD__)
 #include <semaphore.h>
 #endif
 
@@ -63,11 +63,11 @@ public:
 #endif
 	}
 	void leave() {
-#if defined(__linux__)
+#if defined(__linux__) || defined(__FreeBSD__)
 	__sync_synchronize();
 #endif
 		isLocked = 0;
-#if defined(__linux__)
+#if defined(__linux__) || defined(__FreeBSD__)
 	__sync_synchronize();
 #endif
 #if VALGRIND
@@ -117,6 +117,8 @@ private:
 	void* ev;
 #elif defined(__linux__)
 	sem_t sem;
+#elif defined(__FreeBSD__)
+	sem_t sem;
 #elif defined(__APPLE__)
 	mach_port_t self;
 	semaphore_t sem;