diff --git a/types/luxon/index.d.ts b/types/luxon/index.d.ts
index 17706a9002..e96e389894 100644
--- a/types/luxon/index.d.ts
+++ b/types/luxon/index.d.ts
@@ -319,8 +319,8 @@ declare module 'luxon' {
         }
 
         type IntervalObject = {
-            start: DateTime;
-            end: DateTime;
+            start?: DateTime;
+            end?: DateTime;
         };
 
         class Interval {
@@ -338,8 +338,8 @@ declare module 'luxon' {
             ): Interval;
             static fromISO(string: string, options?: DateTimeOptions): Interval;
             static invalid(reason?: string): Interval;
-            static merge(intervals: Interval[]): [Interval];
-            static xor(intervals: Interval[]): [Interval];
+            static merge(intervals: Interval[]): Interval[];
+            static xor(intervals: Interval[]): Interval[];
             end: DateTime;
             invalidReason: string;
             isValid: boolean;
diff --git a/types/luxon/luxon-tests.ts b/types/luxon/luxon-tests.ts
index de0aca9bfd..017f07b0c6 100644
--- a/types/luxon/luxon-tests.ts
+++ b/types/luxon/luxon-tests.ts
@@ -78,6 +78,7 @@ const i = Interval.fromDateTimes(now, later);
 i.length();
 i.length('years');
 i.contains(DateTime.local(2019));
+i.set({end: DateTime.local(2020)});
 
 i.toISO();
 i.toString();