diff --git a/ext/opcache/zend_file_cache.c b/ext/opcache/zend_file_cache.c
index d1ea0a46a6a..7c615e927b4 100644
--- a/ext/opcache/zend_file_cache.c
+++ b/ext/opcache/zend_file_cache.c
@@ -36,6 +36,10 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 
+#if HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
 #ifdef HAVE_SYS_UIO_H
 # include <sys/uio.h>
 #endif