diff --git a/Source/Array.swift b/Source/Array.swift
index 9339e72..5f0f915 100644
--- a/Source/Array.swift
+++ b/Source/Array.swift
@@ -89,7 +89,7 @@ public func <-< <T, U, V>(f: (U) -> [V], g: (T) -> [U]) -> (T) -> [V] {
 
     - returns: The provided value wrapped in an array
 */
-public func pure<T>(a: T) -> [T] {
+public func pure<T>(_ a: T) -> [T] {
     return [a]
 }
 
diff --git a/Source/Optional.swift b/Source/Optional.swift
index d77c9aa..b6b9098 100644
--- a/Source/Optional.swift
+++ b/Source/Optional.swift
@@ -95,7 +95,7 @@ public func <-< <T, U, V>(f: (U) -> V?, g: (T) -> U?) -> (T) -> V? {
 
     - returns: The provided value wrapped in `.Some`
 */
-public func pure<T>(a: T) -> T? {
+public func pure<T>(_ a: T) -> T? {
     return .some(a)
 }