diff --git a/source/gui/GUIManager.cpp b/source/gui/GUIManager.cpp
index 3a0cb7de01..1444382814 100644
--- a/source/gui/GUIManager.cpp
+++ b/source/gui/GUIManager.cpp
@@ -319,7 +319,7 @@ std::string CGUIManager::GetSavedGameData()
 	return scriptInterface->StringifyJSON(&data, false);
 }
 
-void CGUIManager::RestoreSavedGameData(std::string jsonData)
+void CGUIManager::RestoreSavedGameData(const std::string& jsonData)
 {
 	shared_ptr<ScriptInterface> scriptInterface = top()->GetScriptInterface();
 	JSContext* cx = scriptInterface->GetContext();
diff --git a/source/gui/GUIManager.h b/source/gui/GUIManager.h
index 2310756103..b2e409fb50 100644
--- a/source/gui/GUIManager.h
+++ b/source/gui/GUIManager.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2016 Wildfire Games.
+/* Copyright (C) 2017 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -142,7 +142,7 @@ public:
  	 */
 	std::string GetSavedGameData();
 
-	void RestoreSavedGameData(std::string jsonData);
+	void RestoreSavedGameData(const std::string& jsonData);
 
 	/**
 	 * Check if a template with this name exists
diff --git a/source/simulation2/components/tests/test_TerritoryManager.h b/source/simulation2/components/tests/test_TerritoryManager.h
index e218aac75f..6e2fa77453 100644
--- a/source/simulation2/components/tests/test_TerritoryManager.h
+++ b/source/simulation2/components/tests/test_TerritoryManager.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2012 Wildfire Games.
+/* Copyright (C) 2017 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -250,7 +250,7 @@ private:
 	/// Parses a string representation of a grid into an actual Grid structure, such that the (i,j) axes are located in the bottom
 	/// left hand side of the map. Note: leaves all custom bits in the grid values at zero (anything outside
 	/// ICmpTerritoryManager::TERRITORY_PLAYER_MASK).
-	Grid<u8> GetGrid(std::string def, u16 w, u16 h)
+	Grid<u8> GetGrid(const std::string& def, u16 w, u16 h)
 	{
 		Grid<u8> grid(w, h);
 		const char* chars = def.c_str();
@@ -272,7 +272,7 @@ private:
 		return grid;
 	}
 
-	void TestBoundaryPointsEqual(std::vector<CVector2D> points, int expectedPoints[][2])
+	void TestBoundaryPointsEqual(const std::vector<CVector2D>& points, int expectedPoints[][2])
 	{
 		// TODO: currently relies on an exact point match, i.e. expectedPoints must be specified going CCW or CW (depending on
 		// whether we're testing an inner or an outer edge) starting from the exact same point that the algorithm happened to
diff --git a/source/tools/atlas/AtlasUI/ScenarioEditor/Sections/Object/Object.cpp b/source/tools/atlas/AtlasUI/ScenarioEditor/Sections/Object/Object.cpp
index acf306b90c..93c17f8d9b 100644
--- a/source/tools/atlas/AtlasUI/ScenarioEditor/Sections/Object/Object.cpp
+++ b/source/tools/atlas/AtlasUI/ScenarioEditor/Sections/Object/Object.cpp
@@ -1,4 +1,4 @@
-/* Copyright (C) 2015 Wildfire Games.
+/* Copyright (C) 2017 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -483,7 +483,7 @@ ObjectBottomBar::ObjectBottomBar(
 	SetSizer(mainSizer);
 }
 
-static wxControl* CreateTemplateNameObject(wxWindow* parent, const std::string templateName, int counterTemplate)
+static wxControl* CreateTemplateNameObject(wxWindow* parent, const std::string& templateName, int counterTemplate)
 {
 	wxString idTemplate(wxString::FromUTF8(templateName.c_str()));
 	if (counterTemplate > 1)