diff --git a/include/mruby/common.h b/include/mruby/common.h
index c5cfaeb50..59214d3c1 100644
--- a/include/mruby/common.h
+++ b/include/mruby/common.h
@@ -28,6 +28,7 @@
 # define MRB_END_DECL
 #endif
 
+#include <sys/types.h>
 #if defined _MSC_VER
 #include <BaseTsd.h>
 typedef SSIZE_T ssize_t;