diff --git a/borsh/src/schema.rs b/borsh/src/schema.rs
index 8bf695351..66ef6970c 100644
--- a/borsh/src/schema.rs
+++ b/borsh/src/schema.rs
@@ -112,9 +112,8 @@ where
 {
     fn serialize<W: Write>(&self, writer: &mut W) -> IOResult<()> {
         let declaration = self.declaration();
-        let definitions: BTreeMap<Declaration, Definition> = self
+        let definitions: BTreeMap<&Declaration, &Definition> = self
             .definitions()
-            .map(|(k, v)| (k.clone(), v.clone()))
             .collect();
         BorshSerialize::serialize(declaration, writer)?;
         BorshSerialize::serialize(&definitions, writer)?;