https://bugs.gentoo.org/707172
--- a/mod_nss.h
+++ b/mod_nss.h
@@ -376,8 +376,8 @@ typedef struct {
  */
 
 /* pool and hash to store ServerName and NSSNickname pairs for SNI */
-apr_pool_t *mp;
-apr_hash_t *ht;
+extern apr_pool_t *mp;
+extern apr_hash_t *ht;
 
 /* Compatibility between Apache 2.0.x and 2.2.x. The numeric version of
  * the version first appeared in Apache 2.0.56-dev. I picked 2.0.55 as it