diff --git a/include/bluez-dbus-cpp/GattApplication1.h b/include/bluez-dbus-cpp/GattApplication1.h
index 2209ab8..82aa17a 100644
--- a/include/bluez-dbus-cpp/GattApplication1.h
+++ b/include/bluez-dbus-cpp/GattApplication1.h
@@ -38,7 +38,7 @@ class GattApplication1 :
 public:
     void addService( std::shared_ptr<GattService1> service )
     {
-        for( auto serv : services_ )
+        for( const auto & serv : services_ )
         {
             if( serv == service )
                 throw std::invalid_argument(std::string("GattApplication::addService '") + service->getPath() + std::string("' already registered!"));
diff --git a/src/GattCharacteristic1.cpp b/src/GattCharacteristic1.cpp
index 097c34f..b4a4b03 100644
--- a/src/GattCharacteristic1.cpp
+++ b/src/GattCharacteristic1.cpp
@@ -107,12 +107,12 @@ void GattCharacteristic1::addFlag( std::string flag )
 
 // ---- Default Handlers -------------------------------------------------------
 
-std::vector<uint8_t> GattCharacteristic1::ReadValue(const std::map<std::string, sdbus::Variant>& options)
+std::vector<uint8_t> GattCharacteristic1::ReadValue(const std::map<std::string, sdbus::Variant>& /*options*/)
 {
     return value_;
 }
 
-void GattCharacteristic1::WriteValue(const std::vector<uint8_t>& value, const std::map<std::string, sdbus::Variant>& options)
+void GattCharacteristic1::WriteValue(const std::vector<uint8_t>& value, const std::map<std::string, sdbus::Variant>& /*options*/)
 {
     value_ = value;
 }
@@ -122,22 +122,22 @@ std::map<sdbus::ObjectPath, std::vector<std::vector<uint8_t>>> GattCharacteristi
     throw sdbus::Error("org.bluez.Error.NotSupported", "Property 'GattCharacteristic1::DirectedValue' not overloaded!");
 }
 
-std::tuple<sdbus::UnixFd, uint16_t> GattCharacteristic1::AcquireWrite(const std::map<std::string, sdbus::Variant>& options)
+std::tuple<sdbus::UnixFd, uint16_t> GattCharacteristic1::AcquireWrite(const std::map<std::string, sdbus::Variant>& /*options*/)
 {
     throw sdbus::Error("org.bluez.Error.NotSupported", "Method 'GattCharacteristic1::AcquireWrite' not overloaded!");
 }
 
-std::tuple<sdbus::UnixFd, uint16_t> GattCharacteristic1::AcquireNotify(const std::map<std::string, sdbus::Variant>& options)
+std::tuple<sdbus::UnixFd, uint16_t> GattCharacteristic1::AcquireNotify(const std::map<std::string, sdbus::Variant>& /*options*/)
 {
     throw sdbus::Error("org.bluez.Error.NotSupported", "Method 'GattCharacteristic1::AcquireNotify' not overloaded!");
 }
 
-void GattCharacteristic1::StartNotify(const std::map<std::string, sdbus::Variant>& options)
+void GattCharacteristic1::StartNotify(const std::map<std::string, sdbus::Variant>& /*options*/)
 {
     notifyingSessions_ += 1;
 }
 
-void GattCharacteristic1::StopNotify(const std::map<std::string, sdbus::Variant>& options)
+void GattCharacteristic1::StopNotify(const std::map<std::string, sdbus::Variant>& /*options*/)
 {
     notifyingSessions_ -= 1;
 }
@@ -152,7 +152,7 @@ void GattCharacteristic1::addDescriptor( std::shared_ptr<GattDescriptor1> descri
 {
     const std::string& descPath = descriptor->getPath();
 
-    for( auto path : includes_ )
+    for( const auto & path : includes_ )
     {
         if( path == descPath )
             throw std::invalid_argument(std::string("GattCharacteristic1::addDescriptor '") + descPath + std::string("' already registered!"));
diff --git a/src/GattService1.cpp b/src/GattService1.cpp
index b7a510f..843f5c1 100644
--- a/src/GattService1.cpp
+++ b/src/GattService1.cpp
@@ -53,7 +53,7 @@ GattService1::~GattService1()
 
 void GattService1::addCharacteristic( std::shared_ptr<GattCharacteristic1> characteristic )
 {
-    for( auto chrc : characteristics_ )
+    for( const auto & chrc : characteristics_ )
     {
         if( chrc == characteristic )
             throw std::invalid_argument(std::string("GattService1::addCharacteristic '") + characteristic->getPath() + std::string("' already registered!"));
@@ -78,7 +78,7 @@ void GattService1::addSubService( std::shared_ptr<GattService1> service )
 {
     const std::string& srvPath = service->getPath();
 
-    for( auto path : includes_ )
+    for( const auto & path : includes_ )
     {
         if( path == srvPath )
             throw std::invalid_argument(std::string("GattService1::addSubService '") + srvPath + std::string("' already registered!"));