diff --git a/src/PickerInput/RangePicker.tsx b/src/PickerInput/RangePicker.tsx
index a850a96cd..43d32233f 100644
--- a/src/PickerInput/RangePicker.tsx
+++ b/src/PickerInput/RangePicker.tsx
@@ -741,7 +741,7 @@ function RangePicker<DateType extends object = any>(
 }
 
 const RefRangePicker = React.forwardRef(RangePicker) as <DateType extends object = any>(
-  props: RangePickerProps<DateType> & { ref?: React.Ref<PickerRef> },
+  props: RangePickerProps<DateType> & React.RefAttributes<PickerRef>,
 ) => React.ReactElement;
 
 if (process.env.NODE_ENV !== 'production') {
diff --git a/src/PickerInput/SinglePicker.tsx b/src/PickerInput/SinglePicker.tsx
index a90f31ec8..ac05fc142 100644
--- a/src/PickerInput/SinglePicker.tsx
+++ b/src/PickerInput/SinglePicker.tsx
@@ -653,7 +653,7 @@ function Picker<DateType extends object = any>(
 }
 
 const RefPicker = React.forwardRef(Picker) as <DateType extends object = any>(
-  props: PickerProps<DateType> & { ref?: React.Ref<PickerRef> },
+  props: PickerProps<DateType> & React.RefAttributes<PickerRef>,
 ) => React.ReactElement;
 
 if (process.env.NODE_ENV !== 'production') {
diff --git a/src/PickerPanel/index.tsx b/src/PickerPanel/index.tsx
index abcb20582..ea067b06b 100644
--- a/src/PickerPanel/index.tsx
+++ b/src/PickerPanel/index.tsx
@@ -417,5 +417,5 @@ if (process.env.NODE_ENV !== 'production') {
 
 // Make support generic
 export default RefPanelPicker as <DateType extends object = any>(
-  props: PickerPanelProps<DateType> & { ref?: React.Ref<PickerPanelRef> },
+  props: PickerPanelProps<DateType> & React.RefAttributes<PickerPanelRef>,
 ) => React.ReactElement;
diff --git a/tests/picker.spec.tsx b/tests/picker.spec.tsx
index 5469f04e9..f6a6bdadd 100644
--- a/tests/picker.spec.tsx
+++ b/tests/picker.spec.tsx
@@ -1262,4 +1262,17 @@ describe('Picker.Basic', () => {
       }),
     );
   });
+
+  it('classNames.popup', () => {
+    render(
+      <DayPicker
+        classNames={{
+          popup: 'bamboo',
+        }}
+        open
+      />,
+    );
+
+    expect(document.querySelector('.rc-picker-dropdown')).toHaveClass('bamboo');
+  });
 });