diff --git a/events/cognito.go b/events/cognito.go
index 0b350a90..373045be 100644
--- a/events/cognito.go
+++ b/events/cognito.go
@@ -121,6 +121,7 @@ type CognitoEventUserPoolsPreSignupResponse struct {
 type CognitoEventUserPoolsPreAuthenticationRequest struct {
 	UserAttributes map[string]string `json:"userAttributes"`
 	ValidationData map[string]string `json:"validationData"`
+	UserNotFound   bool              `json:"userNotFound"`
 }
 
 // CognitoEventUserPoolsPreAuthenticationResponse contains the response portion of a PreAuthentication event
@@ -309,6 +310,7 @@ type CognitoEventUserPoolsCreateAuthChallengeRequest struct {
 	ChallengeName  string                                  `json:"challengeName"`
 	Session        []*CognitoEventUserPoolsChallengeResult `json:"session"`
 	ClientMetadata map[string]string                       `json:"clientMetadata"`
+	UserNotFound   bool                                    `json:"userNotFound"`
 }
 
 // CognitoEventUserPoolsCreateAuthChallengeResponse defines create auth challenge response rarameters
@@ -331,6 +333,7 @@ type CognitoEventUserPoolsVerifyAuthChallengeRequest struct {
 	PrivateChallengeParameters map[string]string `json:"privateChallengeParameters"`
 	ChallengeAnswer            interface{}       `json:"challengeAnswer"`
 	ClientMetadata             map[string]string `json:"clientMetadata"`
+	UserNotFound               bool              `json:"userNotFound"`
 }
 
 // CognitoEventUserPoolsVerifyAuthChallengeResponse defines verify auth challenge response parameters
diff --git a/events/testdata/cognito-event-userpools-create-auth-challenge.json b/events/testdata/cognito-event-userpools-create-auth-challenge.json
index 2d7ca67b..0188f4fa 100644
--- a/events/testdata/cognito-event-userpools-create-auth-challenge.json
+++ b/events/testdata/cognito-event-userpools-create-auth-challenge.json
@@ -26,7 +26,8 @@
     ],
     "clientMetadata": {
       "exampleMetadataKey": "example metadata value"
-    }
+    },
+    "userNotFound": false
   },
   "response": {
     "publicChallengeParameters": {
diff --git a/events/testdata/cognito-event-userpools-preauthentication.json b/events/testdata/cognito-event-userpools-preauthentication.json
index 71e2c352..2041b102 100644
--- a/events/testdata/cognito-event-userpools-preauthentication.json
+++ b/events/testdata/cognito-event-userpools-preauthentication.json
@@ -15,7 +15,8 @@
       "validationData": {
           "k1": "v1",
           "k2": "v2"
-       }
+       },
+      "userNotFound": false
   },
   "response": {}
 }
\ No newline at end of file
diff --git a/events/testdata/cognito-event-userpools-verify-auth-challenge.json b/events/testdata/cognito-event-userpools-verify-auth-challenge.json
index 57b030b9..3f2516cc 100644
--- a/events/testdata/cognito-event-userpools-verify-auth-challenge.json
+++ b/events/testdata/cognito-event-userpools-verify-auth-challenge.json
@@ -22,7 +22,8 @@
     "challengeAnswer": "123xxxx",
     "clientMetadata": {
       "exampleMetadataKey": "example metadata value"
-    }
+    },
+    "userNotFound": false
   },
   "response": {
     "answerCorrect": true