diff --git a/include/site/i486-linux b/include/site/i486-linux
index d22ec208584..7c5773de5d9 100644
--- a/include/site/i486-linux
+++ b/include/site/i486-linux
@@ -23,5 +23,6 @@ ac_cv_sizeof_uint32_t=4
 ac_cv_sizeof_uint64_t=8
 ac_cv_sizeof_unsigned_int=4
 ac_cv_sizeof_unsigned_long=4
+ac_cv_sizeof_unsigned_long_long=8
 ac_cv_sizeof_unsigned_short=2
 ac_cv_sizeof_void_p=4