diff --git a/Objects/fileobject.c b/Objects/fileobject.c
index f5e5c5974c7..2ba63bd16f7 100644
--- a/Objects/fileobject.c
+++ b/Objects/fileobject.c
@@ -36,6 +36,10 @@ PERFORMANCE OF THIS SOFTWARE.
 #include "structmember.h"
 #include "ceval.h"
 
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
 #ifdef THINK_C
 #define HAVE_FOPENRF
 #endif