diff --git a/glfw/backend_utils.c b/glfw/backend_utils.c
index e3885bdf2..a322d095f 100644
--- a/glfw/backend_utils.c
+++ b/glfw/backend_utils.c
@@ -17,6 +17,7 @@
 #include <errno.h>
 #include <time.h>
 #include <stdio.h>
+#include <sys/mman.h>
 
 #ifdef __NetBSD__
 #define ppoll pollts