diff --git a/modules/proxy/mod_proxy.c b/modules/proxy/mod_proxy.c
index a68c8536d1..7188f1c28d 100644
--- a/modules/proxy/mod_proxy.c
+++ b/modules/proxy/mod_proxy.c
@@ -1075,6 +1075,9 @@ static const char *
             const char *err = ap_proxy_add_worker(&worker, cmd->pool, conf, r);
             if (err)
                 return apr_pstrcat(cmd->temp_pool, "ProxyPass ", err, NULL);
+        } else {
+            ap_log_error(APLOG_MARK, APLOG_WARNING, 0, cmd->server,
+                         "worker %s already used by another worker", worker->name);
         }
         PROXY_COPY_CONF_PARAMS(worker, conf);
 
@@ -1468,6 +1471,9 @@ static const char *add_member(cmd_parms *cmd, void *dummy, const char *arg)
         const char *err;
         if ((err = ap_proxy_add_worker(&worker, cmd->pool, conf, name)) != NULL)
             return apr_pstrcat(cmd->temp_pool, "BalancerMember ", err, NULL);
+    } else {
+            ap_log_error(APLOG_MARK, APLOG_WARNING, 0, cmd->server,
+                         "worker %s already used by another worker", worker->name);
     }
     PROXY_COPY_CONF_PARAMS(worker, conf);