diff --git a/lib/model.js b/lib/model.js
index 30a33390d1f..49eef8eadb8 100644
--- a/lib/model.js
+++ b/lib/model.js
@@ -3937,7 +3937,7 @@ function getModelsMapForPopulate(model, docs, options) {
       } else {
         normalizedRef = virtual.options.ref;
       }
-      justOne = virtual.options.justOne;
+      justOne = !!virtual.options.justOne;
       isVirtual = true;
       if (!modelNames) {
         modelNames = [].concat(normalizedRef);
diff --git a/lib/virtualtype.js b/lib/virtualtype.js
index 81ff20dda38..4f1e9d5db80 100644
--- a/lib/virtualtype.js
+++ b/lib/virtualtype.js
@@ -23,7 +23,7 @@ function VirtualType(options, name) {
   this.path = name;
   this.getters = [];
   this.setters = [];
-  this.options = options || {};
+  this.options = Object.assign({}, options);
 }
 
 /**