https://bugs.gentoo.org/707610
--- a/include/mod_auth_xradius.h.in
+++ b/include/mod_auth_xradius.h.in
@@ -41,7 +41,7 @@
  */
 #define HAVE_APR_MEMCACHE    @have_apr_memcache@
 
-module AP_MODULE_DECLARE_DATA auth_xradius_module;
+extern module AP_MODULE_DECLARE_DATA auth_xradius_module;
 
 #define MOD_AUTH_XRADIUS_VERSION "@MOD_AUTH_XRADIUS_VERSION@"
 
--- a/src/mod_auth_xradius.c
+++ b/src/mod_auth_xradius.c
@@ -47,6 +47,7 @@ if (rvx != 0) { \
                       goto run_cleanup; \
 }
 
+module AP_MODULE_DECLARE_DATA auth_xradius_module;
 apr_proc_mutex_t *gmutex;
 static int use_mutex;