diff --git a/src/merge_join.rs b/src/merge_join.rs
index cbbeb28d0..e2bbc0a87 100644
--- a/src/merge_join.rs
+++ b/src/merge_join.rs
@@ -31,6 +31,23 @@ pub struct MergeJoinBy<I: Iterator, J: Iterator, F> {
     cmp_fn: F
 }
 
+impl<I, J, F> Clone for MergeJoinBy<I, J, F>
+where
+    I: Iterator,
+    J: Iterator,
+    PutBack<Fuse<I>>: Clone,
+    PutBack<Fuse<J>>: Clone,
+    F: Clone,
+{
+    fn clone(&self) -> Self {
+        MergeJoinBy {
+            left: self.left.clone(),
+            right: self.right.clone(),
+            cmp_fn: self.cmp_fn.clone(),
+        }
+    }
+}
+
 impl<I, J, F> fmt::Debug for MergeJoinBy<I, J, F>
     where I: Iterator + fmt::Debug,
           I::Item: fmt::Debug,
diff --git a/tests/specializations.rs b/tests/specializations.rs
new file mode 100644
index 000000000..719e348f8
--- /dev/null
+++ b/tests/specializations.rs
@@ -0,0 +1,111 @@
+extern crate itertools;
+
+use itertools::{Itertools, EitherOrBoth};
+
+use std::fmt::Debug;
+use std::ops::BitXor;
+
+struct Unspecialized<I>(I);
+impl<I> Iterator for Unspecialized<I>
+where
+    I: Iterator,
+{
+    type Item = I::Item;
+
+    #[inline(always)]
+    fn next(&mut self) -> Option<I::Item> {
+        self.0.next()
+    }
+
+    #[inline(always)]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.0.size_hint()
+    }
+}
+
+fn check_specialized<'a, V, IterItem, Iter, F>(iterator: &Iter, mapper: F)
+where
+    V: Eq + Debug,
+    IterItem: 'a,
+    Iter: Iterator<Item = IterItem> + Clone + 'a,
+    F: Fn(Box<Iterator<Item = IterItem> + 'a>) -> V,
+{
+    assert_eq!(
+        mapper(Box::new(Unspecialized(iterator.clone()))),
+        mapper(Box::new(iterator.clone()))
+    )
+}
+
+fn check_specialized_count_last_nth_sizeh<'a, IterItem, Iter>(it: &Iter, expected_size: usize)
+where
+    IterItem: 'a + Eq + Debug,
+    Iter: Iterator<Item = IterItem> + Clone + 'a,
+{
+    let size = it.clone().count();
+    assert_eq!(size, expected_size);
+    check_specialized(it, |i| i.count());
+    check_specialized(it, |i| i.last());
+    for n in 0..size + 2 {
+        check_specialized(it, |mut i| i.nth(n));
+    }
+    let mut it_sh = it.clone();
+    for n in 0..size + 2 {
+        let len = it_sh.clone().count();
+        let (min, max) = it_sh.size_hint();
+		assert_eq!((size-n.min(size)), len);
+        assert!(min <= len);
+        if let Some(max) = max {
+            assert!(len <= max);
+        }
+		it_sh.next();
+    }
+}
+
+fn check_specialized_fold_xor<'a, IterItem, Iter>(it: &Iter)
+where
+    IterItem: 'a
+        + BitXor
+        + Eq
+        + Debug
+        + BitXor<<IterItem as BitXor>::Output, Output = <IterItem as BitXor>::Output>
+        + Clone,
+    <IterItem as BitXor>::Output:
+        BitXor<Output = <IterItem as BitXor>::Output> + Eq + Debug + Clone,
+    Iter: Iterator<Item = IterItem> + Clone + 'a,
+{
+    check_specialized(it, |mut i| {
+        let first = i.next().map(|f| f.clone() ^ (f.clone() ^ f));
+        i.fold(first, |acc, v: IterItem| acc.map(move |a| v ^ a))
+    });
+}
+
+#[test]
+fn put_back() {
+    let test_vec = vec![7, 4, 1];
+	{
+		// Lexical lifetimes support
+		let pb = itertools::put_back(test_vec.iter());
+		check_specialized_count_last_nth_sizeh(&pb, 3);
+		check_specialized_fold_xor(&pb);
+	}
+
+    let mut pb = itertools::put_back(test_vec.into_iter());
+    pb.put_back(1);
+    check_specialized_count_last_nth_sizeh(&pb, 4);
+    check_specialized_fold_xor(&pb);
+}
+
+#[test]
+fn merge_join_by() {
+    let i1 = vec![1, 3, 5].into_iter();
+    let i2 = vec![0, 3, 4, 5].into_iter();
+    let mjb = i1.merge_join_by(i2, std::cmp::Ord::cmp);
+    check_specialized_count_last_nth_sizeh(&mjb, 5);
+	// Rust 1.24 compatibility:
+	fn eob_left_z(eob: EitherOrBoth<usize, usize>) -> usize { eob.left().unwrap_or(0) }
+	fn eob_right_z(eob: EitherOrBoth<usize, usize>) -> usize { eob.left().unwrap_or(0) }
+	fn eob_both_z(eob: EitherOrBoth<usize, usize>) -> usize { let (a,b) = eob.both().unwrap_or((0,0)); assert_eq!(a,b); a }
+    check_specialized_fold_xor(&mjb.clone().map(eob_left_z));
+    check_specialized_fold_xor(&mjb.clone().map(eob_right_z));
+    check_specialized_fold_xor(&mjb.clone().map(eob_both_z));
+}