diff --git a/packages/effect-lens/src/Lens.ts b/packages/effect-lens/src/Lens.ts
index 50b629c..728112f 100644
--- a/packages/effect-lens/src/Lens.ts
+++ b/packages/effect-lens/src/Lens.ts
@@ -274,7 +274,7 @@ export const unwrap = <A, ER, EW, RR, RW, E1, R1>(
         effect,
         l => Effect.flatMap(asLensImpl(l).access, frame => frame.commit(Effect.succeed(a))),
     ),
-    withLock: self => Effect.flatMap(effect, l => asLensImpl(l).withLock(self)),
+    withLock: <A1, E1, R1>(self: Effect.Effect<A1, E1, R1>) => Effect.flatMap(effect, l => asLensImpl(l).withLock(self)),
 })
 
 /**