diff --git a/src/basic/def.h b/src/basic/def.h
index 7ce052c7ef..d3f5381e1b 100644
--- a/src/basic/def.h
+++ b/src/basic/def.h
@@ -84,3 +84,5 @@
         "/usr/local/lib/" n "\0"                \
         "/usr/lib/" n "\0"                      \
         _CONF_PATHS_SPLIT_USR(n)
+
+#define LONG_LINE_MAX (1U*1024U*1024U)