diff --git a/CMakeLists.txt b/CMakeLists.txt
index 57e94b8b8..2f4aa6536 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -295,7 +295,7 @@ SET(CMAKE_INSTALL_RPATH_USE_LINK_PATH TRUE)
 ##
 #############################################################
 if ("${CMAKE_GENERATOR}" STREQUAL "Xcode")
-	set(CMAKE_XCODE_ATTRIBUTE_CLANG_CXX_LANGUAGE_STANDARD "c++11")
+	set(CMAKE_XCODE_ATTRIBUTE_CLANG_CXX_LANGUAGE_STANDARD "c++14")
 	set(CMAKE_XCODE_ATTRIBUTE_CLANG_CXX_LIBRARY "libc++")
 endif()
 
diff --git a/src/storm/parser/JaniParser.cpp b/src/storm/parser/JaniParser.cpp
index d743d9ced..4101359d3 100644
--- a/src/storm/parser/JaniParser.cpp
+++ b/src/storm/parser/JaniParser.cpp
@@ -186,7 +186,7 @@ namespace storm {
                     return std::make_shared<storm::logic::AtomicLabelFormula>(propertyStructure.get<std::string>());
                 }
             }
-            storm::expressions::Expression expr = parseExpression(propertyStructure, "expression in property", {}, true);
+            storm::expressions::Expression expr = parseExpression(propertyStructure, "expression in property", std::unordered_map<std::string, std::shared_ptr<storm::jani::Variable>>(), true);
             if(expr.isInitialized()) {
                 assert(bound == boost::none);
                 return std::make_shared<storm::logic::AtomicExpressionFormula>(expr);
diff --git a/src/storm/parser/JaniParser.h b/src/storm/parser/JaniParser.h
index 627a056dd..2ac6c8366 100644
--- a/src/storm/parser/JaniParser.h
+++ b/src/storm/parser/JaniParser.h
@@ -59,8 +59,8 @@ namespace storm {
              */
             void parseActions(json const& actionStructure, storm::jani::Model& parentModel);
             std::shared_ptr<storm::logic::Formula const> parseFormula(json const& propertyStructure, storm::logic::FormulaContext formulaContext, std::string const& context, boost::optional<storm::logic::Bound<storm::RationalNumber>> bound = boost::none);
-            std::vector<storm::expressions::Expression> parseUnaryExpressionArguments(json const& expressionStructure, std::string const& opstring, std::string const& scopeDescription, std::unordered_map<std::string, std::shared_ptr<storm::jani::Variable>> const& localVars = {}, bool returnNoneOnUnknownOpString = false);
-            std::vector<storm::expressions::Expression> parseBinaryExpressionArguments(json const& expressionStructure, std::string const& opstring,  std::string const& scopeDescription, std::unordered_map<std::string, std::shared_ptr<storm::jani::Variable>> const& localVars = {}, bool returnNoneOnUnknownOpString = false);
+            std::vector<storm::expressions::Expression> parseUnaryExpressionArguments(json const& expressionStructure, std::string const& opstring, std::string const& scopeDescription, std::unordered_map<std::string, std::shared_ptr<storm::jani::Variable>> const& localVars = std::unordered_map<std::string, std::shared_ptr<storm::jani::Variable>>(), bool returnNoneOnUnknownOpString = false);
+            std::vector<storm::expressions::Expression> parseBinaryExpressionArguments(json const& expressionStructure, std::string const& opstring,  std::string const& scopeDescription, std::unordered_map<std::string, std::shared_ptr<storm::jani::Variable>> const& localVars = std::unordered_map<std::string, std::shared_ptr<storm::jani::Variable>>(), bool returnNoneOnUnknownOpString = false);
 
             std::vector<std::shared_ptr<storm::logic::Formula const>> parseUnaryFormulaArgument(json const& propertyStructure, storm::logic::FormulaContext formulaContext,  std::string const& opstring, std::string const& context);
             std::vector<std::shared_ptr<storm::logic::Formula const>> parseBinaryFormulaArguments(json const& propertyStructure, storm::logic::FormulaContext formulaContext, std::string const& opstring, std::string const& context);
@@ -68,7 +68,7 @@ namespace storm {
                 
             
             std::shared_ptr<storm::jani::Composition> parseComposition(json const& compositionStructure);
-            storm::expressions::Variable getVariableOrConstantExpression(std::string const& ident, std::string const& scopeDescription, std::unordered_map<std::string, std::shared_ptr<storm::jani::Variable>> const& localVars = {});
+            storm::expressions::Variable getVariableOrConstantExpression(std::string const& ident, std::string const& scopeDescription, std::unordered_map<std::string, std::shared_ptr<storm::jani::Variable>> const& localVars = std::unordered_map<std::string, std::shared_ptr<storm::jani::Variable>>());
 
             
             /**