diff --git a/lib/authn.js b/lib/authn.js
index 0bb4a89..6e66a7a 100644
--- a/lib/authn.js
+++ b/lib/authn.js
@@ -14,15 +14,24 @@ const {util: {BedrockError}} = bedrock;
 
 export async function openDatabase(options) {
   const config = bedrock.config.mongodb;
+
+  let opts;
+  if(config.url) {
+    opts = {
+      // FIXME: temporary experiment
+      url: `${config.url}?authSource=admin`
+    };
+  } else {
   // copy the config stuff related to connecting
-  const opts = {
-    database: config.name,
-    authentication: {...config.authentication},
-    // authSource should be set in connectOptions
-    connectOptions: {...config.connectOptions},
-    writeOptions: {...config.writeOptions},
-    ...options
-  };
+    opts = {
+      database: config.name,
+      authentication: {...config.authentication},
+      // authSource should be set in connectOptions
+      connectOptions: {...config.connectOptions},
+      writeOptions: {...config.writeOptions},
+      ...options
+    };
+  }
 
   // if a `url` was not specified, create one from the `config`
   if(!opts.url) {