diff --git a/src/impls.rs b/src/impls.rs
index 6d35686..d2b86c7 100644
--- a/src/impls.rs
+++ b/src/impls.rs
@@ -67,12 +67,8 @@ unsafe impl<T, I> Trait for ::std::iter::IntoIterator<IntoIter=I, Item=T> { }
 unsafe impl<T> Trait for ::std::iter::Iterator<Item=T> + Send { }
 unsafe impl<T> Trait for ::std::iter::Iterator<Item=T> + Sync { }
 unsafe impl<T> Trait for ::std::iter::Iterator<Item=T> + Send + Sync { }
-unsafe impl Trait for ::std::marker::Send + Send { }
-unsafe impl Trait for ::std::marker::Send + Sync { }
-unsafe impl Trait for ::std::marker::Send + Send + Sync { }
-unsafe impl Trait for ::std::marker::Sync + Send { }
-unsafe impl Trait for ::std::marker::Sync + Sync { }
-unsafe impl Trait for ::std::marker::Sync + Send + Sync { }
+unsafe impl Trait for Send { }
+unsafe impl Trait for Sync { }
 unsafe impl Trait for ::std::ops::Drop + Send { }
 unsafe impl Trait for ::std::ops::Drop + Sync { }
 unsafe impl Trait for ::std::ops::Drop + Send + Sync { }