diff --git a/typings/DateTime.d.ts b/typings/DateTime.d.ts
index 99bbc4134..24c67b157 100644
--- a/typings/DateTime.d.ts
+++ b/typings/DateTime.d.ts
@@ -17,8 +17,8 @@ declare namespace ReactDatetimeClass {
     export type ViewMode = 'years' | 'months' | 'days' | 'time';
 
     export interface TimeConstraint {
-        min: number;
-        max: number;
+        min?: number;
+        max?: number;
         step: number;
     }