diff --git a/.travis.yml b/.travis.yml
index d318d9cc8..132743d34 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,4 +1,3 @@
-
 language: cpp
 
 compiler:
@@ -26,6 +25,7 @@ addons:
       - pkg-config
 
 before_script:
+  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew uninstall libtool; brew install libtool; fi
   - if [ -n "$USE_SHELL" ]; then export CONFIG_SHELL="$USE_SHELL"; fi
   - test -n "$USE_SHELL" && eval '"$USE_SHELL" -c "./autogen.sh"' || ./autogen.sh
 
diff --git a/include/univalue.h b/include/univalue.h
index e48b905bf..e8ce28351 100644
--- a/include/univalue.h
+++ b/include/univalue.h
@@ -142,10 +142,10 @@ private:
 public:
     // Strict type-specific getters, these throw std::runtime_error if the
     // value is of unexpected type
-    std::vector<std::string> getKeys() const;
-    std::vector<UniValue> getValues() const;
+    const std::vector<std::string>& getKeys() const;
+    const std::vector<UniValue>& getValues() const;
     bool get_bool() const;
-    std::string get_str() const;
+    const std::string& get_str() const;
     int get_int() const;
     int64_t get_int64() const;
     double get_real() const;
diff --git a/lib/univalue.cpp b/lib/univalue.cpp
index 1f8cee6d2..5a2860c13 100644
--- a/lib/univalue.cpp
+++ b/lib/univalue.cpp
@@ -283,14 +283,14 @@ const UniValue& find_value(const UniValue& obj, const std::string& name)
     return NullUniValue;
 }
 
-std::vector<std::string> UniValue::getKeys() const
+const std::vector<std::string>& UniValue::getKeys() const
 {
     if (typ != VOBJ)
         throw std::runtime_error("JSON value is not an object as expected");
     return keys;
 }
 
-std::vector<UniValue> UniValue::getValues() const
+const std::vector<UniValue>& UniValue::getValues() const
 {
     if (typ != VOBJ && typ != VARR)
         throw std::runtime_error("JSON value is not an object or array as expected");
@@ -304,7 +304,7 @@ bool UniValue::get_bool() const
     return getBool();
 }
 
-std::string UniValue::get_str() const
+const std::string& UniValue::get_str() const
 {
     if (typ != VSTR)
         throw std::runtime_error("JSON value is not a string as expected");