diff --git a/packages/minimongo/minimongo_tests.js b/packages/minimongo/minimongo_tests.js
index 6a800c2f7d..75c26b8731 100644
--- a/packages/minimongo/minimongo_tests.js
+++ b/packages/minimongo/minimongo_tests.js
@@ -2881,6 +2881,25 @@ Tinytest.add("minimongo - modify", function (test) {
     { $setOnInsert: { a: 123 } },
     { a: 123 },
   );
+  const testDate = new Date('2017-01-01');
+  upsert(
+    { someDate: testDate },
+    { $setOnInsert: { a: 123 } },
+    { someDate: testDate, a: 123 },
+  );
+  upsert(
+    {
+      a: Object.create(null, {
+        $exists: {
+          writable: true,
+          configurable: true,
+          value: true
+        }
+      }),
+    },
+    { $setOnInsert: { a: 123 } },
+    { a: 123 },
+  );
 
   exception({}, {$set: {_id: 'bad'}});
 
diff --git a/packages/minimongo/selector.js b/packages/minimongo/selector.js
index 15fb94d61b..02a702fb10 100644
--- a/packages/minimongo/selector.js
+++ b/packages/minimongo/selector.js
@@ -1251,19 +1251,22 @@ LocalCollection._f = {
   }
 };
 
-// Oddball function used by upsert. Make sure that when we're removing
-// $ operators we don't accidently remove the "oid" (MongoID.ObjectID)
-// EJSON type (which includes $type and $value properties).
-LocalCollection._removeDollarOperators = function (selector) {
-  return EJSON.parse(
-    JSON.stringify(
-      EJSON.toJSONValue(selector),
-      function (key, value) {
-        if (EJSON.fromJSONValue(this) instanceof MongoID.ObjectID
-            || !key.startsWith("$")) {
-          return value;
-        }
+// Oddball function used by upsert.
+LocalCollection._removeDollarOperators = (selector) => {
+  const cleansed = {};
+
+  Object.keys(selector).forEach((key) => {
+    const value = selector[key];
+    if (key.charAt(0) !== '$') {
+      if (value !== null
+          && value.constructor
+          && value.constructor.prototype === Object.prototype) {
+        cleansed[key] = LocalCollection._removeDollarOperators(value);
+      } else {
+        cleansed[key] = value;
       }
-    )
-  );
+    }
+  });
+
+  return cleansed;
 };