diff --git a/packages/mongo-livedata/doc_fetcher.js b/packages/mongo-livedata/doc_fetcher.js
index 11051b6129..a33eabc755 100644
--- a/packages/mongo-livedata/doc_fetcher.js
+++ b/packages/mongo-livedata/doc_fetcher.js
@@ -25,7 +25,7 @@ _.extend(DocFetcher.prototype, {
     // it's done and return whatever it returns.
     if (_.has(self._futuresForCacheKey, cacheKey)) {
       var f = new Future;
-      self._futuresForCacheKey.push(f);
+      self._futuresForCacheKey[cacheKey].push(f);
       return f.wait();
     }
 
diff --git a/packages/mongo-livedata/doc_fetcher_tests.js b/packages/mongo-livedata/doc_fetcher_tests.js
new file mode 100644
index 0000000000..cf4e05a8d0
--- /dev/null
+++ b/packages/mongo-livedata/doc_fetcher_tests.js
@@ -0,0 +1,38 @@
+var Fiber = Npm.require('fibers');
+var Future = Npm.require('fibers/future');
+
+Tinytest.add("mongo-livedata - doc fetcher", function (test) {
+  var collName = "docfetcher-" + Random.id();
+  var collection = new Meteor.Collection(collName);
+  var id1 = collection.insert({x: 1});
+  var id2 = collection.insert({y: 2});
+
+  var fetcher = new MongoTest.DocFetcher(
+    MongoInternals.defaultRemoteCollectionDriver().mongo);
+
+  // Test basic operation.
+  test.equal(fetcher.fetch(collName, id1, Random.id()),
+             {_id: id1, x: 1});
+  test.equal(fetcher.fetch(collName, "nonexistent!", Random.id()), null);
+
+  var future = new Future;
+  var fetched = false;
+  var cacheKey = Random.id();
+  Fiber(function () {
+    var d = fetcher.fetch(collName, id2, cacheKey);
+    fetched = true;
+    future.return(d);
+  }).run();
+  // The fetcher yields:
+  test.isFalse(fetched);
+
+  // Now ask for another document with the same cache key. Because a fetch for
+  // that cache key is in flight, we will get the other fetch's document, not
+  // this random document.
+  var doc2a = fetcher.fetch(collName, Random.id(), cacheKey);
+  // Finally, wait for the original fetch to return:
+  var doc2b = future.wait();
+  var expected = {_id: id2, y: 2};
+  test.equal(doc2a, expected);
+  test.equal(doc2b, expected);
+});
diff --git a/packages/mongo-livedata/mongo_driver.js b/packages/mongo-livedata/mongo_driver.js
index 925cff8b53..19f604b8d0 100644
--- a/packages/mongo-livedata/mongo_driver.js
+++ b/packages/mongo-livedata/mongo_driver.js
@@ -1617,5 +1617,6 @@ MongoInternals.Connection = MongoConnection;
 MongoInternals.NpmModule = MongoDB;
 
 MongoTest = {
-  cursorSupportedByOplogTailing: cursorSupportedByOplogTailing
+  cursorSupportedByOplogTailing: cursorSupportedByOplogTailing,
+  DocFetcher: DocFetcher
 };
diff --git a/packages/mongo-livedata/package.js b/packages/mongo-livedata/package.js
index 5389cd1157..b9179eb05e 100644
--- a/packages/mongo-livedata/package.js
+++ b/packages/mongo-livedata/package.js
@@ -36,7 +36,7 @@ Package.on_use(function (api) {
   // Stuff that should be exposed via a real API, but we haven't yet.
   api.export('MongoInternals', 'server');
   // For tests only.
-  api.export('MongoTest', 'server');
+  api.export('MongoTest', 'server', {testOnly: true});
 
   api.add_files(['id_map.js', 'doc_fetcher.js'], 'server');
   api.add_files('mongo_driver.js', 'server');
@@ -57,4 +57,5 @@ Package.on_test(function (api) {
   api.add_files('collection_tests.js', ['client', 'server']);
   api.add_files('observe_changes_tests.js', ['client', 'server']);
   api.add_files('oplog_tests.js', 'server');
+  api.add_files('doc_fetcher_tests.js', 'server');
 });