diff --git a/x-pack/filebeat/input/httpjson/config.go b/x-pack/filebeat/input/httpjson/config.go
index ee1445b8a3d..6384811aaa4 100644
--- a/x-pack/filebeat/input/httpjson/config.go
+++ b/x-pack/filebeat/input/httpjson/config.go
@@ -125,10 +125,15 @@ func (dc *dateCursorConfig) Validate() error {
 	if dc.DateFormat == "" {
 		return nil
 	}
-	now := time.Now().Format(dc.DateFormat)
-	if _, err := time.Parse(dc.DateFormat, now); err != nil {
+
+	const knownTimestamp = 1602601228 // 2020-10-13T15:00:28+00:00 RFC3339
+	knownDate := time.Unix(knownTimestamp, 0).UTC()
+
+	dateStr := knownDate.Format(dc.DateFormat)
+	if _, err := time.Parse(dc.DateFormat, dateStr); err != nil {
 		return errors.New("invalid configuration: date_format is not a valid date layout")
 	}
+
 	return nil
 }
 
diff --git a/x-pack/filebeat/input/httpjson/config_test.go b/x-pack/filebeat/input/httpjson/config_test.go
index 1986ee7abe9..85c7c64848d 100644
--- a/x-pack/filebeat/input/httpjson/config_test.go
+++ b/x-pack/filebeat/input/httpjson/config_test.go
@@ -362,7 +362,6 @@ func TestConfigOauth2Validation(t *testing.T) {
 				"url": "localhost",
 			},
 		},
-		/* Flaky test: https://github.com/elastic/beats/issues/21748
 		{
 			name:        "date_cursor.date_format will fail if invalid",
 			expectedErr: "invalid configuration: date_format is not a valid date layout accessing 'date_cursor'",
@@ -371,7 +370,6 @@ func TestConfigOauth2Validation(t *testing.T) {
 				"url":         "localhost",
 			},
 		},
-		*/
 		{
 			name: "date_cursor must work with a valid date_format",
 			input: map[string]interface{}{