diff --git a/configure.ac b/configure.ac
index 0095c4e..ab0fa19 100644
--- a/configure.ac
+++ b/configure.ac
@@ -63,6 +63,7 @@ AC_TYPE_UINT16_T
 AC_TYPE_UINT32_T
 AC_TYPE_UINT64_T
 AC_TYPE_INT32_T
+AC_TYPE_OFF_T
 
 AC_TYPE_SIGNAL