diff --git a/src/filesys/off_t.h b/src/filesys/off_t.h
new file mode 100644
index 0000000000000000000000000000000000000000..9caff4dbae88823f109b1d3ee99c7535f79a55ce
--- /dev/null
+++ b/src/filesys/off_t.h
@@ -0,0 +1,15 @@
+#ifndef FILESYS_OFF_T_H
+#define FILESYS_OFF_T_H
+
+#include <stdint.h>
+
+/* An offset within a file.
+   This is a separate header because multiple headers want this
+   definition but not any others. */
+typedef int32_t off_t;
+
+/* Format specifier for printf(), e.g.:
+   printf ("offset=%"PROTd"\n", offset); */
+#define PROTd PRId32
+
+#endif /* filesys/off_t.h */