diff --git a/configure.ac b/configure.ac
index 0e0e175..eb47c03 100644
--- a/configure.ac
+++ b/configure.ac
@@ -90,6 +90,7 @@
 AC_TYPE_MODE_T
 AC_TYPE_OFF_T
 AC_TYPE_SIZE_T
+AC_TYPE_SSIZE_T
 AC_TYPE_UINT16_T
 AC_TYPE_UINT32_T
 AC_TYPE_UINT64_T