diff --git a/src/kernel/expr.cpp b/src/kernel/expr.cpp
index 83346152f1..434a49bf42 100644
--- a/src/kernel/expr.cpp
+++ b/src/kernel/expr.cpp
@@ -149,7 +149,7 @@ void expr_app::dealloc(buffer<expr_cell*> & todelete) {
 // Expr binders (Lambda, Pi and Sigma)
 expr_binder::expr_binder(expr_kind k, name const & n, expr const & t, expr const & b):
     expr_composite(k, ::lean::hash(t.hash(), b.hash()), t.has_metavar() || b.has_metavar(),
-                   std::max(get_depth(m_domain), get_depth(m_body)) + 1),
+                   std::max(get_depth(t), get_depth(b)) + 1),
     m_name(n),
     m_domain(t),
     m_body(b) {
diff --git a/src/kernel/instantiate.cpp b/src/kernel/instantiate.cpp
index 65eafe0abf..010cdabf3d 100644
--- a/src/kernel/instantiate.cpp
+++ b/src/kernel/instantiate.cpp
@@ -93,7 +93,7 @@ expr head_beta_reduce(expr const & t) {
         expr const * it = &t;
         while (true) {
             lean_assert(is_app(*it));
-            expr f = app_fn(*it);
+            expr const & f = app_fn(*it);
             args.push_back(app_arg(*it));
             if (is_lambda(f)) {
                 return apply_beta(f, args.size(), args.data());