diff --git a/os-posix.c b/os-posix.c
index e3ed497224..daf3d6f6f3 100644
--- a/os-posix.c
+++ b/os-posix.c
@@ -44,6 +44,10 @@
 #include <sys/prctl.h>
 #endif
 
+#ifdef __FreeBSD__
+#include <sys/sysctl.h>
+#endif
+
 static struct passwd *user_pwd;
 static const char *chroot_dir;
 static int daemonize;