https://bugs.gentoo.org/706988
--- a/srvrlib/db.c
+++ b/srvrlib/db.c
@@ -65,7 +65,7 @@ struct timeval db_time;
 
 int db_debug;
 
-u_char grey_on;
+extern u_char grey_on;
 
 DB_BUF_MODE db_buf_mode_hash, db_buf_mode_db;
 
--- a/thrlib/cmn_defs.h
+++ b/thrlib/cmn_defs.h
@@ -237,7 +237,7 @@ extern u_int dcc_ctxt_sn;		/* change X-DCC header server name */
 
 extern RCPT_ST *rcpt_st_free;
 
-const char *userdirs;
+extern const char *userdirs;
 
 extern u_char dcc_query_only;
 extern u_char can_discard_1;		/* 1=can trim targets after DATA */