diff --git a/io.cpp b/io.cpp
index e5d5a0c10..6a304014c 100644
--- a/io.cpp
+++ b/io.cpp
@@ -166,12 +166,6 @@ void io_chain_t::remove(const shared_ptr<const io_data_t> &element)
     }
 }
 
-io_chain_t io_chain_t::duplicate() const
-{
-    io_chain_t result = *this;
-    return result;
-}
-
 void io_chain_t::duplicate_prepend(const io_chain_t &src)
 {
     /* Prepend a duplicate of src before this. */
@@ -188,11 +182,6 @@ void io_remove(io_chain_t &list, const shared_ptr<const io_data_t> &element)
     list.remove(element);
 }
 
-io_chain_t io_duplicate(const io_chain_t &chain)
-{
-    return chain.duplicate();
-}
-
 void io_print(const io_chain_t &chain)
 {
     if (chain.empty())
diff --git a/io.h b/io.h
index 1d31a14ff..34dc242bd 100644
--- a/io.h
+++ b/io.h
@@ -135,9 +135,6 @@ class io_chain_t : public std::vector<shared_ptr<io_data_t> >
 */
 void io_remove(io_chain_t &list, const shared_ptr<const io_data_t> &element);
 
-/** Make a copy of the specified chain of redirections. Uses operator new. */
-io_chain_t io_duplicate(const io_chain_t &chain);
-
 /** Return a shallow copy of the specified chain of redirections that contains only the applicable redirections. That is, if there's multiple redirections for the same fd, only the second one is included. */
 io_chain_t io_unique(const io_chain_t &chain);