diff --git a/packages/mongo-livedata/mongo_driver.js b/packages/mongo-livedata/mongo_driver.js
index aca94e98dc..815c4a1636 100644
--- a/packages/mongo-livedata/mongo_driver.js
+++ b/packages/mongo-livedata/mongo_driver.js
@@ -154,10 +154,7 @@ MongoConnection = function (url, connectionOptions) {
   // settle a little before thinking too hard about this
   if (process.env.XXX_OPLOG_URL && !connectionOptions.isOplog) {
     var dbName = Npm.require('url').parse(url).pathname.substr(1);
-    // Defer this, because it blocks. If we start observing cursors before the
-    // oplog handle is ready, they just don't get to use the oplog.
-    Meteor.defer(_.bind(self._startOplogTailing,
-                        self, process.env.XXX_OPLOG_URL, dbName));
+    self._startOplogTailing(process.env.XXX_OPLOG_URL, dbName);
   }
 };
 
@@ -259,75 +256,99 @@ MongoConnection.prototype._callWhenOplogProcessed = function (callback) {
 MongoConnection.prototype._startOplogTailing = function (oplogUrl, dbName) {
   var self = this;
 
-  var oplogConnection = new MongoConnection(oplogUrl, {isOplog: true});
-  // Find the last oplog entry. Blocks until the connection is ready.
-
-  var lastOplogEntry = oplogConnection.findOne(
-    OPLOG_COLLECTION, {}, {sort: {$natural: -1}});
-
-  var oplogSelector = {
-    ns: new RegExp('^' + quotemeta(dbName) + '\\.'),
-    // XXX also handle drop collection, etc
-    op: {$in: ['i', 'u', 'd']}
-  };
-  if (lastOplogEntry)
-    oplogSelector.ts = {$gt: lastOplogEntry.ts};
-
-  var cursorDescription = new CursorDescription(
-    OPLOG_COLLECTION, oplogSelector, {tailable: true});
-
+  var stopped = false;
+  var tailHandle = null;
+  var readyFuture = new Future();
+  var nextId = 0;
   var callbacksByCollection = {};
 
-  var processSequence = function (doc) {
-    if (doc.op !== 'i' && doc.op !== 'u')
-      return;
-    var serverId = (doc.op === 'i' ? doc.o._id : doc.o2._id);
-    if (serverId !== myServerId)
-      return;
-    var sequenceId =
-          (doc.op === 'i' ? doc.o.sequence : (doc.o.$set && doc.o.$set.sequence));
-    if (typeof sequenceId !== 'number')
-      return;
-    // Process all sequence points up to this point.
-    while (!_.isEmpty(pendingSequences)
-           && pendingSequences[0].sequenceId <= sequenceId) {
-      var sequence = pendingSequences.shift();
-      sequence.callback();
+  self._oplogHandle = {
+    stop: function () {
+      if (stopped)
+        return;
+      stopped = true;
+      if (tailHandle)
+        tailHandle.stop();
+    },
+
+    onOplogEntry: function (collectionName, callback) {
+      if (stopped)
+        throw new Error("Called onOplogEntry on stopped handle!");
+
+      // Calling onOplogEntry requires us to wait for the tailing to be ready.
+      readyFuture.wait();
+
+      callback = Meteor.bindEnvironment(callback, function (err) {
+        Meteor._debug("Error in oplog callback", err.stack);
+      });
+      if (!_.has(callbacksByCollection, collectionName))
+        callbacksByCollection[collectionName] = {};
+      var callbackId = nextId++;
+      callbacksByCollection[collectionName][callbackId] = callback;
+      return {
+        stop: function () {
+          delete callbacksByCollection[collectionName][callbackId];
+        }
+      };
     }
   };
 
-  self._oplogHandle = oplogConnection.tail(cursorDescription, function (doc) {
-    if (!doc.ns && doc.ns.length > dbName.length + 1 &&
-        doc.ns.substr(0, dbName.length + 1) === (dbName + '.'))
-      throw new Error("Unexpected ns");
+  // Actually setting up the connection and tail blocks, so we do it "later".
+  Meteor.defer(function () {
+    var oplogConnection = new MongoConnection(oplogUrl, {isOplog: true});
 
-    var collectionName = doc.ns.substr(dbName.length + 1);
+    // Find the last oplog entry. Blocks until the connection is ready.
+    var lastOplogEntry = oplogConnection.findOne(
+      OPLOG_COLLECTION, {}, {sort: {$natural: -1}});
 
-    if (collectionName === SEQUENCE_COLLECTION) {
-      processSequence(doc);
-      return;
-    }
+    var oplogSelector = {
+      ns: new RegExp('^' + quotemeta(dbName) + '\\.'),
+      // XXX also handle drop collection, etc
+      op: {$in: ['i', 'u', 'd']}
+    };
+    if (lastOplogEntry)
+      oplogSelector.ts = {$gt: lastOplogEntry.ts};
 
-    _.each(callbacksByCollection[collectionName], function (callback) {
-      callback(EJSON.clone(doc));
-    });
-  });
+    var cursorDescription = new CursorDescription(
+      OPLOG_COLLECTION, oplogSelector, {tailable: true});
 
-  var nextId = 0;
-  self._oplogHandle.onOplogEntry = function (collectionName, callback) {
-    callback = Meteor.bindEnvironment(callback, function (err) {
-      Meteor._debug("Error in oplog callback", err.stack);
-    });
-    if (!_.has(callbacksByCollection, collectionName))
-      callbacksByCollection[collectionName] = {};
-    var callbackId = nextId++;
-    callbacksByCollection[collectionName][callbackId] = callback;
-    return {
-      stop: function () {
-        delete callbacksByCollection[collectionName][callbackId];
+    var processSequence = function (doc) {
+      if (doc.op !== 'i' && doc.op !== 'u')
+        return;
+      var serverId = (doc.op === 'i' ? doc.o._id : doc.o2._id);
+      if (serverId !== myServerId)
+        return;
+      var sequenceId =
+            (doc.op === 'i' ? doc.o.sequence :
+             (doc.o.$set && doc.o.$set.sequence));
+      if (typeof sequenceId !== 'number')
+        return;
+      // Process all sequence points up to this point.
+      while (!_.isEmpty(pendingSequences)
+             && pendingSequences[0].sequenceId <= sequenceId) {
+        var sequence = pendingSequences.shift();
+        sequence.callback();
       }
     };
-  };
+
+    tailHandle = oplogConnection.tail(cursorDescription, function (doc) {
+      if (!doc.ns && doc.ns.length > dbName.length + 1 &&
+          doc.ns.substr(0, dbName.length + 1) === (dbName + '.'))
+        throw new Error("Unexpected ns");
+
+      var collectionName = doc.ns.substr(dbName.length + 1);
+
+      if (collectionName === SEQUENCE_COLLECTION) {
+        processSequence(doc);
+        return;
+      }
+
+      _.each(callbacksByCollection[collectionName], function (callback) {
+        callback(EJSON.clone(doc));
+      });
+    });
+    readyFuture.return();
+  });
 };