diff --git a/packages/web/src/react/index.test.tsx b/packages/web/src/react/index.test.tsx
index fdcdcab..2320eee 100644
--- a/packages/web/src/react/index.test.tsx
+++ b/packages/web/src/react/index.test.tsx
@@ -60,5 +60,18 @@ describe('<SpeedInsights />', () => {
       expect(window.siq?.[0]).toEqual(['beforeSend', beforeSend2]);
       expect(window.siq).toHaveLength(1);
     });
+
+    it('does not change beforeSend when undefined', () => {
+      const beforeSend: Required<SpeedInsightsProps>['beforeSend'] = (event) =>
+        event;
+      const { rerender } = render(<SpeedInsights beforeSend={beforeSend} />);
+
+      expect(window.siq?.[0]).toEqual(['beforeSend', beforeSend]);
+      expect(window.siq).toHaveLength(1);
+      window.siq?.splice(0, 1);
+
+      rerender(<SpeedInsights />);
+      expect(window.siq).toHaveLength(0);
+    });
   });
 });
diff --git a/packages/web/src/react/index.tsx b/packages/web/src/react/index.tsx
index 2200281..8214f8b 100644
--- a/packages/web/src/react/index.tsx
+++ b/packages/web/src/react/index.tsx
@@ -9,7 +9,9 @@ export function SpeedInsights(
   },
 ): JSX.Element | null {
   useEffect(() => {
-    window.si?.('beforeSend', props.beforeSend);
+    if (props.beforeSend) {
+      window.si?.('beforeSend', props.beforeSend);
+    }
   }, [props.beforeSend]);
 
   const setScriptRoute = useRef<((path: string) => void) | null>(null);