diff --git a/packages/minimongo/minimongo.js b/packages/minimongo/minimongo.js
index 91cfffb794..bf89da0771 100644
--- a/packages/minimongo/minimongo.js
+++ b/packages/minimongo/minimongo.js
@@ -623,7 +623,7 @@ LocalCollection.prototype._modifyAndNotify = function (
       // in the output. So it's safe to skip recompute if neither before or
       // after are true.)
       if (before || after)
-	recomputeQids[qid] = true;
+        recomputeQids[qid] = true;
     } else if (before && !after) {
       LocalCollection._removeFromResults(query, doc);
     } else if (!before && after) {
@@ -1069,7 +1069,7 @@ LocalCollection._compileProjection = function (fields) {
   var _idProjection = _.isUndefined(fields._id) ? true : fields._id;
   delete fields._id;
   var including = null; // Unknown
-  var projectionRules = [];
+  var projectionRulesTree = {}; // Tree represented as nested objects
 
   _.each(fields, function (rule, keyPath) {
     rule = !!rule;
@@ -1078,74 +1078,47 @@ LocalCollection._compileProjection = function (fields) {
     if (including !== rule)
       // This error message is copies from MongoDB shell
       throw MinimongoError("You cannot currently mix including and excluding fields.");
-    projectionRules.push(keyPath.split('.'));
+    var treePos = projectionRulesTree;
+    keyPath = keyPath.split('.');
+
+    _.each(keyPath.slice(0, -1), function (key) {
+      if (!_.has(treePos, key))
+        treePos[key] = {};
+      treePos = treePos[key];
+    });
+
+    treePos[_.last(keyPath)] = including;
   });
 
-  // XXX do these functions share too much in common?
-  if (including)
-    return function (doc) {
-      var result = {};
+  // returns transformed doc according to ruleTree
+  var transform = function (doc, ruleTree) {
+    var res = including ? {} : EJSON.clone(doc);
+    _.each(ruleTree, function (rule, key) {
+      if (!_.has(doc, key))
+        return;
+      if (_.isObject(rule)) {
+        if (_.isArray(doc[key]))
+          res[key] = _.map(doc[key], function (subdoc) {
+            return transform(subdoc, rule);
+          });
+        else if (_.isObject(doc[key]))
+          res[key] = transform(doc[key], rule);
+      } else if (including)
+        res[key] = doc[key];
+      else
+        delete res[key];
+    });
+    
+    return res;
+  };
 
-      _.each(projectionRules, function (keyPath) {
-        var target = result;
-        var docTarget = doc;
-        for (var i = 0; i < keyPath.length - 1; i++) {
-          var key = keyPath[i];
-          // This block simulates MongoDB behavior for different edge-cases when
-          // object on certain path wasn't found or array found instead of an
-          // object, or vice-versa.
-          if (!_.has(target, key)) {
-            if (_.isArray(docTarget[key])) {
-              target[key] = [];
-              docTarget = undefined;
-              break;
-            } else if (_.isObject(docTarget[key]))
-              target[key] = {};
-            else {
-              docTarget = undefined;
-              break;
-            }
-          }
-
-          target = target[key];
-          docTarget = docTarget[key];
-        }
-
-        if (keyPath.length > 0 && docTarget && _.has(docTarget, _.last(keyPath)))
-          target[_.last(keyPath)] = docTarget[_.last(keyPath)];
-      });
-
-      if (_idProjection && _.has(doc, '_id'))
-        result._id = doc._id;
-
-      return result;
-    };
-  else
-    return function (doc) {
-      // XXX Deep copy on this level might be a slowing factor,
-      // In fact we need it only in case of nested excluded fields.
-      var result = EJSON.clone(doc);
-
-      _.each(projectionRules, function (keyPath) {
-        var target = result;
-        var docTarget = doc;
-        for (var i = 0; i < keyPath.length - 1; i++) {
-          var key = keyPath[i];
-          if (!_.has(target, key)) {
-            break;
-          }
-
-          target = target[key];
-          docTarget = docTarget[key];
-        }
-
-        if (keyPath.length > 0)
-          delete target[_.last(keyPath)];
-      });
-
-      if (!_idProjection)
-        delete result._id;
-
-      return result;
-    };
+  return function (obj) {
+    var res = transform(obj, projectionRulesTree);
+    
+    if (_idProjection && _.has(obj, '_id'))
+      res._id = obj._id;
+    if (!_idProjection && _.has(res, '_id'))
+      delete res._id;
+    return res;
+  };
 };