diff --git a/ext/mini_racer_extension/mini_racer_extension.cc b/ext/mini_racer_extension/mini_racer_extension.cc
index 67c882e..5869e84 100644
--- a/ext/mini_racer_extension/mini_racer_extension.cc
+++ b/ext/mini_racer_extension/mini_racer_extension.cc
@@ -5,6 +5,7 @@
 #include <include/libplatform/libplatform.h>
 #include <ruby/encoding.h>
 #include <pthread.h>
+#include <unistd.h>
 
 using namespace v8;