diff --git a/src/func.rs b/src/func.rs
index 0be33e1..8c8e20b 100644
--- a/src/func.rs
+++ b/src/func.rs
@@ -7,7 +7,7 @@ pub mod test_suite;
 pub mod tests;
 
 pub trait WeakFunctor {
-    type F<'a, A: 'a> : 'a;
+    type F<'a, A: 'a>: 'a;
 }
 
 /// Rust-specific implementation of [Functor], respecting `move` semantics.