diff --git a/.vscode/settings.json b/.vscode/settings.json
index 1ac79ad19..21c5c7441 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -3,7 +3,7 @@
   "editor.defaultFormatter": "esbenp.prettier-vscode",
   "eslint.validate": ["typescript"],
   "editor.codeActionsOnSave": {
-    "source.fixAll.eslint": true
+    "source.fixAll.eslint": "explicit"
   },
   "files.insertFinalNewline": true
 }
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 88b4dea4a..4ab28d5b3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,6 +16,12 @@
 **Note**: A feature tagged as Experimental is in a
 high state of flux, you're at risk of it changing without notice.
 
+# 2.16.4
+
+**Polish**
+
+Fix `__PURE__` annotation placement, closes #1926
+
 # 2.16.3
 
 **Polish**
diff --git a/package.json b/package.json
index d69dbb4f6..b2473de22 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "fp-ts",
-  "version": "2.16.3",
+  "version": "2.16.4",
   "description": "Functional programming in TypeScript",
   "main": "./lib/index.js",
   "module": "./es6/index.js",
diff --git a/src/IOEither.ts b/src/IOEither.ts
index f42c6a0ff..f37881919 100644
--- a/src/IOEither.ts
+++ b/src/IOEither.ts
@@ -840,8 +840,7 @@ export const chainOptionK: <E>(
  */
 export const chainOptionKW: <E2>(
   onNone: LazyArg<E2>
-) => <A, B>(f: (a: A) => Option<B>) => <E1>(ma: IOEither<E1, A>) => IOEither<E1 | E2, B> =
-  /*#__PURE__*/ chainOptionK as any
+) => <A, B>(f: (a: A) => Option<B>) => <E1>(ma: IOEither<E1, A>) => IOEither<E1 | E2, B> = chainOptionK as any
 
 /** @internal */
 interface IOEitherTypeLambda extends _.TypeLambda {
diff --git a/src/ReaderEither.ts b/src/ReaderEither.ts
index c495311ad..08e7684d6 100644
--- a/src/ReaderEither.ts
+++ b/src/ReaderEither.ts
@@ -861,7 +861,7 @@ export const chainOptionK: <E>(
 export const chainOptionKW: <E2>(
   onNone: LazyArg<E2>
 ) => <A, B>(f: (a: A) => Option<B>) => <R, E1>(ma: ReaderEither<R, E1, A>) => ReaderEither<R, E1 | E2, B> =
-  /*#__PURE__*/ chainOptionK as any
+  chainOptionK as any
 
 /** @internal */
 interface ReaderEitherTypeLambda extends _.TypeLambda {
diff --git a/src/ReaderIO.ts b/src/ReaderIO.ts
index 1e0ab45fd..9610c757f 100644
--- a/src/ReaderIO.ts
+++ b/src/ReaderIO.ts
@@ -48,7 +48,7 @@ export const fromReader: <R, A>(fa: Reader<R, A>) => ReaderIO<R, A> = /*#__PURE_
  * @category conversions
  * @since 2.13.0
  */
-export const fromIO: <A, R = unknown>(fa: IO<A>) => ReaderIO<R, A> = /*#__PURE__*/ R.of
+export const fromIO: <A, R = unknown>(fa: IO<A>) => ReaderIO<R, A> = R.of
 
 // -------------------------------------------------------------------------------------
 // combinators
diff --git a/src/ReaderTask.ts b/src/ReaderTask.ts
index 0fab18fc9..7b7fe25b9 100644
--- a/src/ReaderTask.ts
+++ b/src/ReaderTask.ts
@@ -64,7 +64,7 @@ export const fromReader: <R, A>(fa: R.Reader<R, A>) => ReaderTask<R, A> = /*#__P
  * @category conversions
  * @since 2.3.0
  */
-export const fromTask: <A, R = unknown>(fa: Task<A>) => ReaderTask<R, A> = /*#__PURE__*/ R.of
+export const fromTask: <A, R = unknown>(fa: Task<A>) => ReaderTask<R, A> = R.of
 
 /**
  * @category conversions
diff --git a/src/ReaderTaskEither.ts b/src/ReaderTaskEither.ts
index 3d3d76800..c6f092a0c 100644
--- a/src/ReaderTaskEither.ts
+++ b/src/ReaderTaskEither.ts
@@ -175,17 +175,15 @@ export const leftIO: <R, E = never, A = never>(me: IO<E>) => ReaderTaskEither<R,
  * @category constructors
  * @since 2.13.0
  */
-export const rightReaderIO: <R, E = never, A = never>(ma: ReaderIO<R, A>) => ReaderTaskEither<R, E, A> = /*#__PURE__*/ (
-  ma
-) => flow(ma, TE.rightIO)
+export const rightReaderIO: <R, E = never, A = never>(ma: ReaderIO<R, A>) => ReaderTaskEither<R, E, A> = (ma) =>
+  flow(ma, TE.rightIO)
 
 /**
  * @category constructors
  * @since 2.13.0
  */
-export const leftReaderIO: <R, E = never, A = never>(me: ReaderIO<R, E>) => ReaderTaskEither<R, E, A> = /*#__PURE__*/ (
-  me
-) => flow(me, TE.leftIO)
+export const leftReaderIO: <R, E = never, A = never>(me: ReaderIO<R, E>) => ReaderTaskEither<R, E, A> = (me) =>
+  flow(me, TE.leftIO)
 
 // -------------------------------------------------------------------------------------
 // conversions
@@ -1381,7 +1379,7 @@ export const chainOptionK: <E>(
 export const chainOptionKW: <E2>(
   onNone: LazyArg<E2>
 ) => <A, B>(f: (a: A) => Option<B>) => <R, E1>(ma: ReaderTaskEither<R, E1, A>) => ReaderTaskEither<R, E1 | E2, B> =
-  /*#__PURE__*/ chainOptionK as any
+  chainOptionK as any
 
 /** @internal */
 interface ReaderTaskEitherTypeLambda extends _.TypeLambda {
diff --git a/src/StateReaderTaskEither.ts b/src/StateReaderTaskEither.ts
index 303af902a..6c6c5feff 100644
--- a/src/StateReaderTaskEither.ts
+++ b/src/StateReaderTaskEither.ts
@@ -1149,8 +1149,7 @@ export const chainOptionKW: <E2>(
   onNone: LazyArg<E2>
 ) => <A, B>(
   f: (a: A) => Option<B>
-) => <S, R, E1>(ma: StateReaderTaskEither<S, R, E1, A>) => StateReaderTaskEither<S, R, E1 | E2, B> =
-  /*#__PURE__*/ chainOptionK as any
+) => <S, R, E1>(ma: StateReaderTaskEither<S, R, E1, A>) => StateReaderTaskEither<S, R, E1 | E2, B> = chainOptionK as any
 
 /**
  * Alias of `flatMapEither`.
diff --git a/src/TaskEither.ts b/src/TaskEither.ts
index e17a1a3d7..28235f17f 100644
--- a/src/TaskEither.ts
+++ b/src/TaskEither.ts
@@ -1149,8 +1149,7 @@ export const chainOptionK: <E>(
  */
 export const chainOptionKW: <E2>(
   onNone: LazyArg<E2>
-) => <A, B>(f: (a: A) => Option<B>) => <E1>(ma: TaskEither<E1, A>) => TaskEither<E1 | E2, B> =
-  /*#__PURE__*/ chainOptionK as any
+) => <A, B>(f: (a: A) => Option<B>) => <E1>(ma: TaskEither<E1, A>) => TaskEither<E1 | E2, B> = chainOptionK as any
 
 /** @internal */
 interface TaskEitherTypeLambda extends _.TypeLambda {
diff --git a/src/TaskThese.ts b/src/TaskThese.ts
index 1d61e9475..3a700af13 100644
--- a/src/TaskThese.ts
+++ b/src/TaskThese.ts
@@ -114,7 +114,7 @@ export const fromIO: <A, E = never>(fa: IO<A>) => TaskThese<E, A> = rightIO
  * @category conversions
  * @since 2.4.0
  */
-export const fromIOEither: <E, A>(fa: IOEither<E, A>) => TaskThese<E, A> = /*#__PURE__*/ T.fromIO
+export const fromIOEither: <E, A>(fa: IOEither<E, A>) => TaskThese<E, A> = T.fromIO
 
 /**
  * @category conversions