diff --git a/packages/mongo/collection_tests.js b/packages/mongo/collection_tests.js
index 055aebb8b6..e8cf45143d 100644
--- a/packages/mongo/collection_tests.js
+++ b/packages/mongo/collection_tests.js
@@ -1,5 +1,5 @@
 
-var MongoDB = NpmModuleMongodb;
+var MongoDB = Meteor.isServer && NpmModuleMongodb;
 
 Tinytest.add(
   'collection - call Mongo.Collection without new',
diff --git a/packages/mongo/mongo_livedata_tests.js b/packages/mongo/mongo_livedata_tests.js
index d458565588..118d16bb1b 100644
--- a/packages/mongo/mongo_livedata_tests.js
+++ b/packages/mongo/mongo_livedata_tests.js
@@ -799,111 +799,118 @@ _.each( ['STRING', 'MONGO'], function(idGeneration) {
       }
     );
 
-    Tinytest.addAsync("mongo-livedata - cursor dedup, " + idGeneration, function (test, onComplete) {
-      var run = test.runId();
-      var coll = new Mongo.Collection("cursorDedup-"+run, collectionOptions);
+    Tinytest.addAsync(
+      'mongo-livedata - cursor dedup, ' + idGeneration,
+      async function(test, onComplete) {
+        var run = test.runId();
+        var coll = new Mongo.Collection(
+          'cursorDedup-' + run,
+          collectionOptions
+        );
 
-      var observer = function (noAdded) {
-        var output = [];
-        var callbacks = {
-          changed: function (newDoc) {
-            output.push({changed: newDoc._id});
-          }
-        };
-        if (!noAdded) {
-          callbacks.added = function (doc) {
-            output.push({added: doc._id});
+        const observer = async function(noAdded, name) {
+          const output = [];
+          const callbacks = {
+            changed: function(newDoc) {
+              output.push({ changed: newDoc._id });
+            },
           };
-        }
-        var handle = coll.find({foo: 22}).observe(callbacks);
-        return {output: output, handle: handle};
-      };
+          if (!noAdded) {
+            callbacks.added = function(doc) {
+              output.push({ added: doc._id });
+            };
+          }
+          const handle = await coll.find({ foo: 22 }).observe(callbacks);
+          return { output: output, handle: handle };
+        };
 
-      // Insert a doc and start observing.
-      var docId1 = coll.insert({foo: 22});
-      var o1 = observer();
-      // Initial add.
-      test.length(o1.output, 1);
-      test.equal(o1.output.shift(), {added: docId1});
+        // Insert a doc and start observing.
+        var docId1 = await coll.insertAsync({ foo: 22 });
+        var o1 = await observer(false, 'o1');
+        // Initial add.
+        test.length(o1.output, 1);
+        test.equal(o1.output.shift(), { added: docId1 });
 
-      // Insert another doc (blocking until observes have fired).
-      var docId2;
-      runInFence(function () {
-        docId2 = coll.insert({foo: 22, bar: 5});
-      });
-      // Observed add.
-      test.length(o1.output, 1);
-      test.equal(o1.output.shift(), {added: docId2});
+        // Insert another doc (blocking until observes have fired).
+        var docId2;
+        await runInFence(async function() {
+          docId2 = await coll.insertAsync({ foo: 22, bar: 5 });
+        });
+        // Observed add.
+        test.length(o1.output, 1);
+        test.equal(o1.output.shift(), { added: docId2 });
 
-      // Second identical observe.
-      var o2 = observer();
-      // Initial adds.
-      test.length(o2.output, 2);
-      test.include([docId1, docId2], o2.output[0].added);
-      test.include([docId1, docId2], o2.output[1].added);
-      test.notEqual(o2.output[0].added, o2.output[1].added);
-      o2.output.length = 0;
-      // Original observe not affected.
-      test.length(o1.output, 0);
+        // Second identical observe.
+        var o2 = await observer(false, 'o2');
 
-      // White-box test: both observes should share an ObserveMultiplexer.
-      var observeMultiplexer = o1.handle._multiplexer;
-      test.isTrue(observeMultiplexer);
-      test.isTrue(observeMultiplexer === o2.handle._multiplexer);
+        // Initial adds.
+        test.length(o2.output, 2);
+        test.include([docId1, docId2], o2.output[0].added);
 
-      // Update. Both observes fire.
-      runInFence(function () {
-        coll.update(docId1, {$set: {x: 'y'}});
-      });
-      test.length(o1.output, 1);
-      test.length(o2.output, 1);
-      test.equal(o1.output.shift(), {changed: docId1});
-      test.equal(o2.output.shift(), {changed: docId1});
+        test.include([docId1, docId2], o2.output[1].added);
+        test.notEqual(o2.output[0].added, o2.output[1].added);
+        o2.output.length = 0;
+        // Original observe not affected.
+        test.length(o1.output, 0);
 
-      // Stop first handle. Second handle still around.
-      o1.handle.stop();
-      test.length(o1.output, 0);
-      test.length(o2.output, 0);
+        // White-box test: both observes should share an ObserveMultiplexer.
+        var observeMultiplexer = o1.handle._multiplexer;
+        test.isTrue(observeMultiplexer);
+        test.isTrue(observeMultiplexer === o2.handle._multiplexer);
 
-      // Another update. Just the second handle should fire.
-      runInFence(function () {
-        coll.update(docId2, {$set: {z: 'y'}});
-      });
-      test.length(o1.output, 0);
-      test.length(o2.output, 1);
-      test.equal(o2.output.shift(), {changed: docId2});
+        // Update. Both observes fire.
+        await runInFence(async function() {
+          await coll.updateAsync(docId1, { $set: { x: 'y' } });
+        });
+        test.length(o1.output, 1);
+        test.length(o2.output, 1);
+        test.equal(o1.output.shift(), { changed: docId1 });
+        test.equal(o2.output.shift(), { changed: docId1 });
 
-      // Stop second handle. Nothing should happen, but the multiplexer should
-      // be stopped.
-      test.isTrue(observeMultiplexer._handles);  // This will change.
-      o2.handle.stop();
-      test.length(o1.output, 0);
-      test.length(o2.output, 0);
-      // White-box: ObserveMultiplexer has nulled its _handles so you can't
-      // accidentally join to it.
-      test.isNull(observeMultiplexer._handles);
+        // Stop first handle. Second handle still around.
+        o1.handle.stop();
+        test.length(o1.output, 0);
+        test.length(o2.output, 0);
 
-      // Start yet another handle on the same query.
-      var o3 = observer();
-      // Initial adds.
-      test.length(o3.output, 2);
-      test.include([docId1, docId2], o3.output[0].added);
-      test.include([docId1, docId2], o3.output[1].added);
-      test.notEqual(o3.output[0].added, o3.output[1].added);
-      // Old observers not called.
-      test.length(o1.output, 0);
-      test.length(o2.output, 0);
-      // White-box: Different ObserveMultiplexer.
-      test.isTrue(observeMultiplexer !== o3.handle._multiplexer);
+        // Another update. Just the second handle should fire.
+        await runInFence(async function() {
+          await coll.updateAsync(docId2, { $set: { z: 'y' } });
+        });
+        test.length(o1.output, 0);
+        test.length(o2.output, 1);
+        test.equal(o2.output.shift(), { changed: docId2 });
 
-      // Start another handle with no added callback. Regression test for #589.
-      var o4 = observer(true);
+        // Stop second handle. Nothing should happen, but the multiplexer should
+        // be stopped.
+        test.isTrue(observeMultiplexer._handles); // This will change.
+        await o2.handle.stop();
+        test.length(o1.output, 0);
+        test.length(o2.output, 0);
+        // White-box: ObserveMultiplexer has nulled its _handles so you can't
+        // accidentally join to it.
+        test.isNull(observeMultiplexer._handles);
+        // Start yet another handle on the same query.
+        var o3 = await observer();
+        // Initial adds.
+        test.length(o3.output, 2);
+        test.include([docId1, docId2], o3.output[0].added);
+        test.include([docId1, docId2], o3.output[1].added);
+        test.notEqual(o3.output[0].added, o3.output[1].added);
+        // Old observers not called.
+        test.length(o1.output, 0);
+        test.length(o2.output, 0);
+        // White-box: Different ObserveMultiplexer.
+        test.isTrue(observeMultiplexer !== o3.handle._multiplexer);
 
-      o3.handle.stop();
-      o4.handle.stop();
+        // Start another handle with no added callback. Regression test for #589.
+        var o4 = await observer(true);
 
-      onComplete();
-    });
+        o3.handle.stop();
+        o4.handle.stop();
+
+        onComplete();
+      }
+    );
 
     Tinytest.addAsync("mongo-livedata - async server-side insert, " + idGeneration, function (test, onComplete) {
       // Tests that insert returns before the callback runs. Relies on the fact
diff --git a/packages/mongo/oplog_observe_driver.js b/packages/mongo/oplog_observe_driver.js
index 13fbb4df55..482fae7133 100644
--- a/packages/mongo/oplog_observe_driver.js
+++ b/packages/mongo/oplog_observe_driver.js
@@ -83,7 +83,6 @@ OplogObserveDriver = function (options) {
   Package['facts-base'] && Package['facts-base'].Facts.incrementServerFact(
     "mongo-livedata", "observe-drivers-oplog", 1);
 
-  self._registerPhaseChange(PHASE.QUERYING);
 
   self._matcher = options.matcher;
   // we are now using projection, not fields in the cursor description even if you pass {fields}
@@ -824,8 +823,10 @@ _.extend(OplogObserveDriver.prototype, {
 
     if (self._stopped)
       return;
-    if (self._phase !== PHASE.QUERYING)
-      throw Error("Phase unexpectedly " + self._phase);
+    // TODO[fibers] not sure about this change. For now it doesn't seems to affect other parts
+    self._registerPhaseChange(PHASE.QUERYING);
+    // if (self._phase !== PHASE.QUERYING)
+    //   throw Error("Phase unexpectedly " + self._phase);
 
     if (self._requeryWhenDoneThisQuery) {
       self._requeryWhenDoneThisQuery = false;