diff --git a/.gitignore b/.gitignore
index 8aaf98d..d801187 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,3 +4,4 @@ node_modules
 coverage
 browser
 .vscode
+.dccache
diff --git a/package.json b/package.json
index 08dd04d..5bae143 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "firebase-mock",
-  "version": "2.3.0",
+  "version": "2.3.1",
   "description": "Firebase mock library for writing unit tests",
   "main": "./src",
   "scripts": {
diff --git a/src/firestore-query.js b/src/firestore-query.js
index 6d79663..730a9e4 100644
--- a/src/firestore-query.js
+++ b/src/firestore-query.js
@@ -106,7 +106,7 @@ MockFirestoreQuery.prototype.where = function (property, operator, value) {
   var path = getPropertyPath(property);
 
   // check if unsupported operator
-  if (operator !== '==' && operator !== 'array-contains') {
+  if (operator !== '==' && operator !== 'array-contains' && operator !== 'in') {
     console.warn('Using unsupported where() operator for firebase-mock, returning entire dataset');
   } else {
     if (_.size(this.data) !== 0) {
@@ -124,6 +124,11 @@ MockFirestoreQuery.prototype.where = function (property, operator, value) {
               results[key] = _.cloneDeep(data);
             }
             break;
+          case 'in':
+            if (_.includes(value, _.get(data, property))) {
+              results[key] = _.cloneDeep(data);
+            }
+            break;
           default:
             results[key] = _.cloneDeep(data);
             break;