From f4df90d6acb61588bdb6623c97b94b4fa718b3d9 Mon Sep 17 00:00:00 2001
From: Leonardo de Moura <leonardo@microsoft.com>
Date: Thu, 2 Jun 2016 17:40:09 -0700
Subject: [PATCH] fix(kernel/declaration): bug at use_untrusted

---
 src/kernel/declaration.cpp | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/src/kernel/declaration.cpp b/src/kernel/declaration.cpp
index 30ab58a3c7..6791e88d3a 100644
--- a/src/kernel/declaration.cpp
+++ b/src/kernel/declaration.cpp
@@ -107,10 +107,11 @@ static bool use_untrusted(environment const & env, expr const & e) {
     for_each(e, [&](expr const & e, unsigned) {
             if (found) return false;
             if (is_constant(e)) {
-                declaration const & d = env.get(const_name(e));
-                if (!d.is_trusted()) {
-                    found = true;
-                    return false;
+                if (auto d = env.find(const_name(e))) {
+                    if (!d->is_trusted()) {
+                        found = true;
+                        return false;
+                    }
                 }
             }
             return true;