diff --git a/yamllint/rules/new_lines.py b/yamllint/rules/new_lines.py
index 0874315..5b95e37 100644
--- a/yamllint/rules/new_lines.py
+++ b/yamllint/rules/new_lines.py
@@ -19,7 +19,7 @@ from yamllint.errors import LintProblem
 
 ID = 'new-lines'
 TYPE = 'line'
-CONF = {'type': str}
+CONF = {'type': ('unix', 'dos')}
 
 
 def check(conf, line):