diff --git a/src/parse.rs b/src/parse.rs
index 1ad1e9b..2525d8f 100644
--- a/src/parse.rs
+++ b/src/parse.rs
@@ -26,7 +26,6 @@
 pub type ParseStream<'a> = &'a ParseBuffer<'a>;
 
 /// Cursor position within a buffered token stream.
-#[derive(Clone)]
 pub struct ParseBuffer<'a> {
     scope: Span,
     cell: Cell<Cursor<'static>>,
@@ -42,6 +41,19 @@
     }
 }
 
+impl<'a> Clone for ParseBuffer<'a> {
+    fn clone(&self) -> Self {
+        ParseBuffer {
+            scope: self.scope,
+            cell: self.cell.clone(),
+            marker: PhantomData,
+            // Not the parent's unexpected. Nothing cares whether the clone
+            // parses all the way.
+            unexpected: Rc::new(Cell::new(None)),
+        }
+    }
+}
+
 // Not public API.
 #[doc(hidden)]
 #[derive(Copy, Clone)]