diff --git a/packages/accounts-password/password_server.js b/packages/accounts-password/password_server.js
index 93af180f05..689cf75f27 100644
--- a/packages/accounts-password/password_server.js
+++ b/packages/accounts-password/password_server.js
@@ -80,7 +80,7 @@ const handleError = (msg, throwError = true) => {
   const error = new Meteor.Error(
     403, 
     Accounts._options.ambiguousErrorMessages
-      ? "Login failure. Please check your login credentials."
+      ? "Something went wrong. Please check your credentials."
       : msg
   );
   if (throwError) {
diff --git a/packages/minimongo/common.js b/packages/minimongo/common.js
index 7aa0cafc27..a0260feebb 100644
--- a/packages/minimongo/common.js
+++ b/packages/minimongo/common.js
@@ -777,8 +777,8 @@ function getValueBitmask(value, length) {
 function insertIntoDocument(document, key, value) {
   Object.keys(document).forEach(existingKey => {
     if (
-      (existingKey.length > key.length && existingKey.indexOf(key) === 0) ||
-      (key.length > existingKey.length && key.indexOf(existingKey) === 0)
+      (existingKey.length > key.length && existingKey.indexOf(`${key}.`) === 0) ||
+      (key.length > existingKey.length && key.indexOf(`${existingKey}.`) === 0)
     ) {
       throw new Error(
         `cannot infer query fields to set, both paths '${existingKey}' and ` +
diff --git a/packages/minimongo/minimongo_tests_client.js b/packages/minimongo/minimongo_tests_client.js
index 776af9aeac..03b2b9dc78 100644
--- a/packages/minimongo/minimongo_tests_client.js
+++ b/packages/minimongo/minimongo_tests_client.js
@@ -3006,7 +3006,10 @@ Tinytest.add('minimongo - modify', test => {
   upsert({"_id": "foo", "foo": "bar"}, {"bar": "foo"}, {"_id": "foo", "bar": "foo"})
    // Replacement update keeps _id
   upsertUpdate({"_id": "foo", "bar": "baz"}, {"_id":"foo"}, {"bar": "crow"}, {"_id": "foo", "bar": "crow"});
-
+  // Test for https://github.com/meteor/meteor/issues/9167
+  upsert({key: 123, keyName: '321'}, {$set: {name: 'Todo'}}, {key: 123, keyName: '321', name: 'Todo'});
+  upsertException({key: 123, "key.name": '321'}, {$set:{}});
+  
   // Nested fields don't work with literal objects
   upsertException({"a": {}, "a.b": "foo"}, {});
    // You can't have an ambiguious ID