diff --git a/include/site/x86_64-linux b/include/site/x86_64-linux
index 62e334c20b..803213c51c 100644
--- a/include/site/x86_64-linux
+++ b/include/site/x86_64-linux
@@ -25,4 +25,4 @@ ac_cv_sizeof_unsigned_int=4
 ac_cv_sizeof_unsigned_long=8
 ac_cv_sizeof_unsigned_long_long=8
 ac_cv_sizeof_unsigned_short=2
-ac_cv_sizeof_void_p=4
+ac_cv_sizeof_void_p=8