diff --git a/Modules/mmapmodule.c b/Modules/mmapmodule.c
index cbacc2f..1d0f490 100644
--- a/Modules/mmapmodule.c
+++ b/Modules/mmapmodule.c
@@ -158,7 +158,8 @@
 #endif /* MS_WINDOWS */
 
 #ifdef UNIX
-	(void) close(self->fd);
+	if (0 <= self->fd)
+		(void) close(self->fd);
 	self->fd = -1;
 	if (self->data != NULL) {
 		munmap(self->data, self->size);