diff --git a/packages/effect-fc-next/src/Component.test.tsx b/packages/effect-fc-next/src/Component.test.tsx
index b15d3ef..69d0063 100644
--- a/packages/effect-fc-next/src/Component.test.tsx
+++ b/packages/effect-fc-next/src/Component.test.tsx
@@ -312,7 +312,7 @@ describe("Component", () => {
                 yield* Effect.addFinalizer(() => Effect.sync(() => unmounts()))
             }))
 
-            return <button onClick={() => setCount(value => value + 1)}>{`${service.value}:${count}`}</button>
+            return <button type="button" onClick={() => setCount(value => value + 1)}>{`${service.value}:${count}`}</button>
         }).pipe(
             Component.withOptions({
                 nonReactiveTags: [...Component.defaultOptions.nonReactiveTags, ValueService],
diff --git a/packages/effect-fc-next/src/Lens.test.tsx b/packages/effect-fc-next/src/Lens.test.tsx
index 82e161d..c59c686 100644
--- a/packages/effect-fc-next/src/Lens.test.tsx
+++ b/packages/effect-fc-next/src/Lens.test.tsx
@@ -18,6 +18,12 @@ const makeRuntime = async () => {
     }
 }
 
+const expectDefined = <A,>(value: A | undefined): A => {
+    if (value === undefined)
+        throw new Error("Expected value to be defined")
+    return value
+}
+
 describe("Lens", () => {
     it("useState stays in sync with lens updates in both directions", async () => {
         const { runtime, effectRuntime, dispose } = await makeRuntime()
@@ -30,7 +36,7 @@ describe("Lens", () => {
             return (
                 <>
                     <div>{value}</div>
-                    <button onClick={() => setValue(previous => previous + 1)}>increment</button>
+                    <button type="button" onClick={() => setValue(previous => previous + 1)}>increment</button>
                 </>
             )
         }).pipe(
@@ -102,7 +108,7 @@ describe("Lens", () => {
                 lens = reactLens
             }))
 
-            return <button onClick={() => setValue(previous => `${previous}!`)}>{value}</button>
+            return <button type="button" onClick={() => setValue(previous => `${previous}!`)}>{value}</button>
         }).pipe(
             Component.withContext(runtime.context)
         )
@@ -118,7 +124,7 @@ describe("Lens", () => {
 
         fireEvent.click(screen.getByRole("button", { name: "hello" }))
         await screen.findByText("hello!")
-        await waitFor(async () => expect(await Effect.runPromise(Lens.get(lens!))).toBe("hello!"))
+        await waitFor(async () => expect(await Effect.runPromise(Lens.get(expectDefined(lens)))).toBe("hello!"))
 
         view.unmount()
         await dispose()
@@ -152,11 +158,11 @@ describe("Lens", () => {
         await screen.findByText("first")
         await waitFor(() => expect(lens).toBeDefined())
 
-        await Effect.runPromise(Lens.set(lens!, { id: 1, label: "ignored" }))
+        await Effect.runPromise(Lens.set(expectDefined(lens), { id: 1, label: "ignored" }))
         await waitFor(() => expect(screen.getByText("first")).toBeTruthy())
         expect(screen.queryByText("ignored")).toBeNull()
 
-        await Effect.runPromise(Lens.set(lens!, { id: 2, label: "updated" }))
+        await Effect.runPromise(Lens.set(expectDefined(lens), { id: 2, label: "updated" }))
         await screen.findByText("updated")
 
         view.unmount()
diff --git a/packages/effect-fc/src/Lens.test.tsx b/packages/effect-fc/src/Lens.test.tsx
index e6ce6bb..e3cff38 100644
--- a/packages/effect-fc/src/Lens.test.tsx
+++ b/packages/effect-fc/src/Lens.test.tsx
@@ -18,6 +18,12 @@ const makeRuntime = async () => {
     }
 }
 
+const expectDefined = <A,>(value: A | undefined): A => {
+    if (value === undefined)
+        throw new Error("Expected value to be defined")
+    return value
+}
+
 describe("Lens", () => {
     it("useState stays in sync with lens updates in both directions", async () => {
         const { runtime, effectRuntime, dispose } = await makeRuntime()
@@ -30,7 +36,7 @@ describe("Lens", () => {
             return (
                 <>
                     <div>{value}</div>
-                    <button onClick={() => setValue(previous => previous + 1)}>increment</button>
+                    <button type="button" onClick={() => setValue(previous => previous + 1)}>increment</button>
                 </>
             )
         }).pipe(
@@ -102,7 +108,7 @@ describe("Lens", () => {
                 lens = reactLens
             }))
 
-            return <button onClick={() => setValue(previous => `${previous}!`)}>{value}</button>
+            return <button type="button" onClick={() => setValue(previous => `${previous}!`)}>{value}</button>
         }).pipe(
             Component.withRuntime(runtime.context)
         )
@@ -118,7 +124,7 @@ describe("Lens", () => {
 
         fireEvent.click(screen.getByRole("button", { name: "hello" }))
         await screen.findByText("hello!")
-        await waitFor(async () => expect(await Effect.runPromise(Lens.get(lens!))).toBe("hello!"))
+        await waitFor(async () => expect(await Effect.runPromise(Lens.get(expectDefined(lens)))).toBe("hello!"))
 
         view.unmount()
         await dispose()
@@ -152,11 +158,11 @@ describe("Lens", () => {
         await screen.findByText("first")
         await waitFor(() => expect(lens).toBeDefined())
 
-        await Effect.runPromise(Lens.set(lens!, { id: 1, label: "ignored" }))
+        await Effect.runPromise(Lens.set(expectDefined(lens), { id: 1, label: "ignored" }))
         await waitFor(() => expect(screen.getByText("first")).toBeTruthy())
         expect(screen.queryByText("ignored")).toBeNull()
 
-        await Effect.runPromise(Lens.set(lens!, { id: 2, label: "updated" }))
+        await Effect.runPromise(Lens.set(expectDefined(lens), { id: 2, label: "updated" }))
         await screen.findByText("updated")
 
         view.unmount()