2 files changed, 2 insertions, 2 deletions
diff --git a/src/eval_env.cc b/src/eval_env.cc
index 8f5c8ee..e03a82e 100644
--- a/src/eval_env.cc
+++ b/src/eval_env.cc
@@ -74,7 +74,7 @@ bool Rule::IsReservedBinding(const string& var) {
       var == "rspfile_content";
 }
 
-const map<string, const Rule*> BindingEnv::GetRules() const {
+const map<string, const Rule*>& BindingEnv::GetRules() const {
   return rules_;
 }
 
diff --git a/src/eval_env.h b/src/eval_env.h
index 250fa55..28c4d16 100644
--- a/src/eval_env.h
+++ b/src/eval_env.h
@@ -84,7 +84,7 @@ struct BindingEnv : public Env {
   void AddRule(const Rule* rule);
   const Rule* LookupRule(const string& rule_name);
   const Rule* LookupRuleCurrentScope(const string& rule_name);
-  const map<string, const Rule*> GetRules() const;
+  const map<string, const Rule*>& GetRules() const;
 
   void AddBinding(const string& key, const string& val);