diff --git a/lib/mongoose-field-encryption.js b/lib/mongoose-field-encryption.js
index f6b1847..d3783f1 100644
--- a/lib/mongoose-field-encryption.js
+++ b/lib/mongoose-field-encryption.js
@@ -194,6 +194,7 @@ const fieldEncryption = function (schema, options) {
 
   function updateHook(_next) {
     const next = getCompatitibleNextFunc(_next);
+    if (this._update === undefined) next();
     for (const field of fieldsToEncrypt) {
       const encryptedFieldName = encryptedFieldNamePrefix + field;
       this._update.$set = this._update.$set || {};