diff --git a/types/sanctuary/index.d.ts b/types/sanctuary/index.d.ts
index 62e7506c30..6f36893eb5 100644
--- a/types/sanctuary/index.d.ts
+++ b/types/sanctuary/index.d.ts
@@ -222,6 +222,8 @@ declare namespace Sanctuary {
     // Either
     isLeft(p: Either<any, any>): boolean;
     isRight(p: Either<any, any>): boolean;
+    fromLeft<A>(p: A): (q: Either<A, any>) => A;
+    fromRight<B>(p: B): (q: Either<any, B>) => B;
     fromEither<B>(p: B): (q: Either<any, B>) => B;
     either<A, C>(p: Fn<A, C>): <B>(q: Fn<B, C>) => (r: Either<A, B>) => C;
     lefts<A>(p: ReadonlyArray<Either<A, any>>): A[];
diff --git a/types/sanctuary/sanctuary-tests.ts b/types/sanctuary/sanctuary-tests.ts
index 4765d8fe3c..0106df1c1c 100644
--- a/types/sanctuary/sanctuary-tests.ts
+++ b/types/sanctuary/sanctuary-tests.ts
@@ -62,3 +62,9 @@ S.intercalate(', ')([]);
 
 // $ExpectType number[]
 S.intercalate([0, 0, 0])([[1], [2, 3], [4, 5, 6], [7, 8], [9]]);
+
+// $ExpectType number
+S.fromLeft(1)(S.Right('a'));
+
+// $ExpectType number
+S.fromRight(1)(S.Left('a'));