diff --git a/include/namespace.h b/include/namespace.h
index 28a4223b..52f7fbd7 100644
--- a/include/namespace.h
+++ b/include/namespace.h
@@ -3,6 +3,7 @@
 
 #include <sched.h>
 #include <sys/mount.h>
+#include <sys/syscall.h>
 #include <errno.h>
 
 #define NETNS_RUN_DIR "/var/run/netns"