diff --git a/libbuild2-autoconf/libbuild2/autoconf/checks/SIZEOF_OFF_T.h b/libbuild2-autoconf/libbuild2/autoconf/checks/SIZEOF_OFF_T.h
new file mode 100644
index 0000000..a7eac23
--- /dev/null
+++ b/libbuild2-autoconf/libbuild2/autoconf/checks/SIZEOF_OFF_T.h
@@ -0,0 +1,15 @@
+// SIZEOF_OFF_T
+
+#undef SIZEOF_OFF_T
+
+/* Note that the _FILE_OFFSET_BITS macro is expected to be defined by the
+ * user, for example, on the command line.
+ */
+
+#ifdef _MSC_VER
+#  define SIZEOF_OFF_T 4
+#elif defined(__x86_64__) || defined(__ppc64__) || (defined(_FILE_OFFSET_BITS) && _FILE_OFFSET_BITS == 64)
+#  define SIZEOF_OFF_T 8
+#else
+#  define SIZEOF_OFF_T 4
+#endif