diff --git a/types/react-dates/index.d.ts b/types/react-dates/index.d.ts
index c3559f5278..dc852dde3b 100644
--- a/types/react-dates/index.d.ts
+++ b/types/react-dates/index.d.ts
@@ -57,6 +57,7 @@ declare namespace ReactDates {
         withPortal?: boolean,
         withFullScreenPortal?: boolean,
         initialVisibleMonth?: () => momentPropTypes.momentObj,
+        firstDayOfWeek? : 0 | 1 | 2 | 3 | 4 | 5 | 6,
         numberOfMonths?: number,
         keepOpenOnDateSelect?: boolean,
         reopenPickerOnClearDates?: boolean,
@@ -144,6 +145,7 @@ declare namespace ReactDates {
         withPortal?: boolean,
         withFullScreenPortal?: boolean,
         initialVisibleMonth?: () => momentPropTypes.momentObj,
+        firstDayOfWeek? : 0 | 1 | 2 | 3 | 4 | 5 | 6,
         numberOfMonths?: number,
         keepOpenOnDateSelect?: boolean,
         reopenPickerOnClearDates?: boolean,
diff --git a/types/react-dates/react-dates-tests.tsx b/types/react-dates/react-dates-tests.tsx
index e8dd3752b3..2c86d07dbe 100644
--- a/types/react-dates/react-dates-tests.tsx
+++ b/types/react-dates/react-dates-tests.tsx
@@ -57,6 +57,7 @@ class SingleDatePickerFullTest extends React.Component {
                     onFocusChange={arg => {}}
                     onNextMonthClick={e => {}}
                     onPrevMonthClick={e => {}}
+                    firstDayOfWeek={0}
                     numberOfMonths={2}
                     orientation="horizontal"
                     monthFormat="MM"
@@ -109,6 +110,7 @@ class DateRangePickerFullTest extends React.Component {
                     onFocusChange={arg => {}}
                     onNextMonthClick={e => {}}
                     onPrevMonthClick={e => {}}
+                    firstDayOfWeek={0}
                     numberOfMonths={2}
                     orientation="horizontal"
                     monthFormat="MM"