diff --git a/src/expr.rs b/src/expr.rs
index fa941e6146a..60e0e007b1d 100644
--- a/src/expr.rs
+++ b/src/expr.rs
@@ -1933,7 +1933,7 @@ fn rewrite_unary_op(
     shape: Shape,
 ) -> Option<String> {
     // For some reason, an UnOp is not spanned like BinOp!
-    rewrite_unary_prefix(context, ast::UnOp::to_string(op), expr, shape)
+    rewrite_unary_prefix(context, op.as_str(), expr, shape)
 }
 
 pub(crate) enum RhsAssignKind<'ast> {
diff --git a/src/pairs.rs b/src/pairs.rs
index 07c05193739..bfc2ffed383 100644
--- a/src/pairs.rs
+++ b/src/pairs.rs
@@ -339,7 +339,7 @@ fn flatten(
                     if let Some(pop) = stack.pop() {
                         match pop.kind {
                             ast::ExprKind::Binary(op, _, ref rhs) => {
-                                separators.push(op.node.to_string());
+                                separators.push(op.node.as_str());
                                 node = rhs;
                             }
                             _ => unreachable!(),