diff --git a/src/Preview.tsx b/src/Preview.tsx
index 7e46aea..b1001ce 100644
--- a/src/Preview.tsx
+++ b/src/Preview.tsx
@@ -324,7 +324,7 @@ const Preview: React.FC<PreviewProps> = props => {
         onFlipX={onFlipX}
         onFlipY={onFlipY}
         onClose={onClose}
-        zIndex={restProps.zIndex}
+        zIndex={restProps.zIndex !== undefined ? restProps.zIndex + 1 : undefined}
       />
     </>
   );
diff --git a/tests/basic.test.tsx b/tests/basic.test.tsx
index 240ae02..44f2618 100644
--- a/tests/basic.test.tsx
+++ b/tests/basic.test.tsx
@@ -95,6 +95,6 @@ describe('Basic', () => {
       />,
     );
     const operationsElement = baseElement.querySelector('.rc-image-preview-operations-wrapper');
-    expect(operationsElement).toHaveStyle({ zIndex: 9999 });
+    expect(operationsElement).toHaveStyle({ zIndex: 10000 });
   });
 });