diff --git a/gameheaders/stratagus-game-launcher.h b/gameheaders/stratagus-game-launcher.h
index 8772b83866..4df276852e 100644
--- a/gameheaders/stratagus-game-launcher.h
+++ b/gameheaders/stratagus-game-launcher.h
@@ -384,9 +384,9 @@ static void ExtractData(char *extractor_tool,
 				}
 			} else {
 				// we cannot test if this is an innoextract installer, assume not but maybe warn
-				if (datafile.compare("INSTALL.EXE") == 0 || datafile.compare("install.exe") == 0
-				    || datafile.compare("INSTALL.exe") == 0 || datafile.compare("SETUP.EXE") == 0
-				    || datafile.compare("setup.exe") == 0 || datafile.compare("SETUP.exe") == 0) {
+				if (datafile == "INSTALL.EXE" || datafile == "install.exe"
+				    || datafile == "INSTALL.exe" || datafile == "SETUP.EXE"
+				    || datafile == "setup.exe" || datafile == "SETUP.exe") {
 					// probably not a packaged installer
 				} else {
 					// warn
diff --git a/src/action/actions.cpp b/src/action/actions.cpp
index 74ed143557..c33705bea6 100644
--- a/src/action/actions.cpp
+++ b/src/action/actions.cpp
@@ -33,11 +33,6 @@
 --  Includes
 ----------------------------------------------------------------------------*/
 
-#include <time.h>
-
-#include "stratagus.h"
-#include "version.h"
-
 #include "actions.h"
 
 #include "action/action_attack.h"
@@ -58,7 +53,6 @@
 #include "action/action_train.h"
 #include "action/action_unload.h"
 #include "action/action_upgradeto.h"
-
 #include "animation/animation_die.h"
 #include "commands.h"
 #include "game.h"
@@ -71,19 +65,23 @@
 #include "player.h"
 #include "script.h"
 #include "spells.h"
+#include "stratagus.h"
 #include "unit.h"
 #include "unit_find.h"
 #include "unit_manager.h"
 #include "unittype.h"
+#include "version.h"
 
 #ifdef USE_STACKTRACE
-#include <stdexcept>
-#include <stacktrace/call_stack.hpp>
-#include <stacktrace/stack_exception.hpp>
+# include <stacktrace/call_stack.hpp>
+# include <stacktrace/stack_exception.hpp>
+# include <stdexcept>
 #else
-#include "st_backtrace.h"
+# include "st_backtrace.h"
 #endif
 
+#include <ctime>
+
 /*----------------------------------------------------------------------------
 --  Variables
 ----------------------------------------------------------------------------*/
diff --git a/src/ai/ai_force.cpp b/src/ai/ai_force.cpp
index 1b37dc10ce..abfcba055a 100644
--- a/src/ai/ai_force.cpp
+++ b/src/ai/ai_force.cpp
@@ -412,10 +412,9 @@ bool AiForce::NewRallyPoint(const Vec2i &startPos, Vec2i *resultPos)
 
 void AiForce::Attack(const Vec2i &pos)
 {
-	bool isDefenceForce = false;
 	RemoveDeadUnit();
 
-	if (Units.size() == 0) {
+	if (Units.empty()) {
 		this->Attacking = false;
 		this->State = AiForceAttackingState::Waiting;
 		return;
@@ -424,7 +423,7 @@ void AiForce::Attack(const Vec2i &pos)
 		// Remember the original force position so we can return there after attack
 		if (this->Role == AiForceRole::Defend
 			|| (this->Role == AiForceRole::Attack && this->State == AiForceAttackingState::Waiting)) {
-			this->HomePos = this->Units[this->Units.size() - 1]->tilePos;
+			this->HomePos = this->Units.back()->tilePos;
 		}
 		this->Attacking = true;
 	}
@@ -436,6 +435,7 @@ void AiForce::Attack(const Vec2i &pos)
 	const bool isTransporter = ranges::any_of(this->Units, [](const CUnit *unit) {
 		return unit->Type->CanTransport() && unit->IsAgressive() == false;
 	});
+	bool isDefenceForce = false;
 	if (Map.Info.IsPointOnMap(goalPos) == false) {
 		/* Search in entire map */
 		const CUnit *enemy = nullptr;
diff --git a/src/animation/animation_die.cpp b/src/animation/animation_die.cpp
index 53e843ee74..dc6b34f2c3 100644
--- a/src/animation/animation_die.cpp
+++ b/src/animation/animation_die.cpp
@@ -33,13 +33,12 @@
 --  Includes
 ----------------------------------------------------------------------------*/
 
-#include "stratagus.h"
-
 #include "animation/animation_die.h"
 
+#include "stratagus.h"
 #include "unit.h"
 
-#include <stdio.h>
+#include <cstdio>
 
 void CAnimation_Die::Action(CUnit &unit, int & /*move*/, int /*scale*/) const /* override */
 {
diff --git a/src/animation/animation_setplayervar.cpp b/src/animation/animation_setplayervar.cpp
index 97c240ce7d..5a5382afd5 100644
--- a/src/animation/animation_setplayervar.cpp
+++ b/src/animation/animation_setplayervar.cpp
@@ -33,15 +33,14 @@
 --  Includes
 ----------------------------------------------------------------------------*/
 
-#include "stratagus.h"
-
 #include "animation/animation_setplayervar.h"
 
 #include "animation.h"
+#include "stratagus.h"
 #include "unit.h"
 
+#include <cstdio>
 #include <sstream>
-#include <stdio.h>
 
 /**
 **  Gets the player data.
diff --git a/src/animation/animation_setvar.cpp b/src/animation/animation_setvar.cpp
index d6340ad019..92a7da9d6a 100644
--- a/src/animation/animation_setvar.cpp
+++ b/src/animation/animation_setvar.cpp
@@ -33,16 +33,14 @@
 --  Includes
 ----------------------------------------------------------------------------*/
 
-#include "stratagus.h"
-
 #include "animation/animation_setvar.h"
 
 #include "actions.h"
+#include "map.h"
 #include "unit.h"
 #include "unit_manager.h"
-#include "map.h"
 
-#include <stdio.h>
+#include <cstdio>
 #include <sstream>
 
 void CAnimation_SetVar::Action(CUnit &unit, int & /*move*/, int /*scale*/) const /* override */
diff --git a/src/game/replay.cpp b/src/game/replay.cpp
index 0a9921a2aa..32a4f993d1 100644
--- a/src/game/replay.cpp
+++ b/src/game/replay.cpp
@@ -32,8 +32,6 @@
 // Includes
 //----------------------------------------------------------------------------
 
-#include "stratagus.h"
-
 #include "replay.h"
 
 #include "actions.h"
@@ -56,8 +54,8 @@
 #include "unittype.h"
 #include "version.h"
 
+#include <ctime>
 #include <sstream>
-#include <time.h>
 
 extern fs::path ExpandPath(const std::string &path);
 extern void StartMap(const std::string &filename, bool clean);
diff --git a/src/game/savegame.cpp b/src/game/savegame.cpp
index ec1ffa9947..db0bb0a741 100644
--- a/src/game/savegame.cpp
+++ b/src/game/savegame.cpp
@@ -54,7 +54,7 @@
 #include "upgrade.h"
 #include "version.h"
 
-#include <time.h>
+#include <ctime>
 
 extern void StartMap(const std::string &filename, bool clean);
 
diff --git a/src/include/interface.h b/src/include/interface.h
index ac6cfa94b3..d2049c723e 100644
--- a/src/include/interface.h
+++ b/src/include/interface.h
@@ -39,8 +39,10 @@
 #include "icons.h"
 #endif
 
+#include "stratagus.h"
 #include "unitsound.h"
 #include "vec2i.h"
+
 #include <optional>
 #include <vector>
 
diff --git a/src/include/iolib.h b/src/include/iolib.h
index 8b1e5bbe1e..16ca55fff1 100644
--- a/src/include/iolib.h
+++ b/src/include/iolib.h
@@ -37,6 +37,7 @@
 ----------------------------------------------------------------------------*/
 
 #include "filesystem.h"
+#include "stratagus.h"
 
 #include <SDL.h>
 #include <memory>
diff --git a/src/include/luacallback.h b/src/include/luacallback.h
index 4c8951cfbe..5ad80307be 100644
--- a/src/include/luacallback.h
+++ b/src/include/luacallback.h
@@ -30,6 +30,7 @@
 #define LUA_CALLBACK_HEADER_FILE
 
 #include <map>
+#include <memory>
 #include <string>
 #include <string_view>
 #include <tuple>
diff --git a/src/include/sdl2_helper.h b/src/include/sdl2_helper.h
index 0632e4e79a..ee8a3a0c76 100644
--- a/src/include/sdl2_helper.h
+++ b/src/include/sdl2_helper.h
@@ -29,6 +29,7 @@
 
 #include <SDL.h>
 #include <memory>
+#include <vector>
 
 //@{
 
diff --git a/src/include/unitptr.h b/src/include/unitptr.h
index 565309815f..f3bf836605 100644
--- a/src/include/unitptr.h
+++ b/src/include/unitptr.h
@@ -32,6 +32,8 @@
 
 //@{
 
+#include <cstddef>
+
 class CUnit;
 
 
diff --git a/src/include/unittype.h b/src/include/unittype.h
index 177b08ccb0..0242294751 100644
--- a/src/include/unittype.h
+++ b/src/include/unittype.h
@@ -52,6 +52,7 @@
 #include "luacallback.h"
 #include "missileconfig.h"
 #include "spells.h"
+#include "stratagus.h"
 #include "util.h"
 #include "vec2i.h"
 
diff --git a/src/include/upgrade_structs.h b/src/include/upgrade_structs.h
index 7a579b5087..020d0be34f 100644
--- a/src/include/upgrade_structs.h
+++ b/src/include/upgrade_structs.h
@@ -37,6 +37,9 @@
 --  Includes
 ----------------------------------------------------------------------------*/
 
+#include "settings.h"
+
+#include <cstring>
 #include <memory>
 #include <vector>
 
diff --git a/src/include/util.h b/src/include/util.h
index 2b0ea321ce..13f05e94da 100644
--- a/src/include/util.h
+++ b/src/include/util.h
@@ -82,7 +82,7 @@ extern uint32_t fletcher32(const std::string &content);
 --  Strings
 ----------------------------------------------------------------------------*/
 
-#include <string.h>
+#include <cstring>
 
 #ifndef _TRUNCATE
 #define _TRUNCATE ((size_t)-1)
diff --git a/src/map/fow.cpp b/src/map/fow.cpp
index f1a9d769f2..8a809f9380 100644
--- a/src/map/fow.cpp
+++ b/src/map/fow.cpp
@@ -34,18 +34,17 @@
 --  Includes
 ----------------------------------------------------------------------------*/
 
-#include <string.h>
-#include <algorithm>
-
-#include "stratagus.h"
-
 #include "fow.h"
+
+#include "../video/intern_video.h"
 #include "map.h"
 #include "player.h"
+#include "stratagus.h"
 #include "tile.h"
 #include "ui.h"
 #include "viewport.h"
-#include "../video/intern_video.h"
+
+#include <algorithm>
 
 /*----------------------------------------------------------------------------
 --  Defines
diff --git a/src/map/fow_utils.cpp b/src/map/fow_utils.cpp
index 01fe7b1665..3ddbf90813 100644
--- a/src/map/fow_utils.cpp
+++ b/src/map/fow_utils.cpp
@@ -33,12 +33,12 @@
 --  Includes
 ----------------------------------------------------------------------------*/
 
-#include <string.h>
-#include <algorithm>
+#include "fow_utils.h"
 
 #include "stratagus.h"
-#include "fow_utils.h"
 
+#include <algorithm>
+#include <cstring>
 
 /*----------------------------------------------------------------------------
 --  Defines
diff --git a/src/map/map_wall.cpp b/src/map/map_wall.cpp
index 1ea7a4ebc3..f71ed14bb5 100644
--- a/src/map/map_wall.cpp
+++ b/src/map/map_wall.cpp
@@ -33,16 +33,16 @@
 -- Includes
 ----------------------------------------------------------------------------*/
 
-#include <stdio.h>
-
-#include "stratagus.h"
-#include "map.h"
 #include "fov.h"
+#include "map.h"
+#include "player.h"
+#include "stratagus.h"
 #include "tileset.h"
 #include "ui.h"
-#include "player.h"
 #include "unittype.h"
 
+#include <cstdio>
+
 /*----------------------------------------------------------------------------
 -- Functions
 ----------------------------------------------------------------------------*/
diff --git a/src/map/script_tileset.cpp b/src/map/script_tileset.cpp
index 7eca3eb27c..4790a7997c 100644
--- a/src/map/script_tileset.cpp
+++ b/src/map/script_tileset.cpp
@@ -42,8 +42,8 @@
 #include "video.h"
 
 #include <SDL_image.h>
+#include <cmath>
 #include <cstring>
-#include <math.h>
 #include <set>
 
 /*----------------------------------------------------------------------------
diff --git a/src/map/tileset.cpp b/src/map/tileset.cpp
index 32bd271af4..d6b4c166f8 100644
--- a/src/map/tileset.cpp
+++ b/src/map/tileset.cpp
@@ -185,7 +185,7 @@
 
 #include "tileset.h"
 
-#include <limits.h>
+#include <climits>
 
 /*----------------------------------------------------------------------------
 -- Variables
diff --git a/src/missile/missile.cpp b/src/missile/missile.cpp
index 4432a2509a..33a8cb7457 100644
--- a/src/missile/missile.cpp
+++ b/src/missile/missile.cpp
@@ -33,10 +33,6 @@
 --  Includes
 ----------------------------------------------------------------------------*/
 
-#include <math.h>
-
-#include "stratagus.h"
-
 #include "missile.h"
 
 #include "action/action_spellcast.h"
@@ -57,6 +53,8 @@
 #include "unittype.h"
 #include "video.h"
 
+#include <cmath>
+
 /*----------------------------------------------------------------------------
 --  Declarations
 ----------------------------------------------------------------------------*/
diff --git a/src/missile/missile_parabolic.cpp b/src/missile/missile_parabolic.cpp
index aac0b696e2..908e173d96 100644
--- a/src/missile/missile_parabolic.cpp
+++ b/src/missile/missile_parabolic.cpp
@@ -33,16 +33,14 @@
 --  Includes
 ----------------------------------------------------------------------------*/
 
-#include <stdio.h>
-
-#include "stratagus.h"
-
-#include "missile.h"
-
 #include "luacallback.h"
 #include "map.h"
+#include "missile.h"
+#include "stratagus.h"
 #include "unit_find.h"
 
+#include <cstdio>
+
 /**
 **  Calculate parabolic trajectories.
 **
diff --git a/src/missile/missile_tracer.cpp b/src/missile/missile_tracer.cpp
index 61a065eb0e..661b64b979 100644
--- a/src/missile/missile_tracer.cpp
+++ b/src/missile/missile_tracer.cpp
@@ -33,17 +33,14 @@
 --  Includes
 ----------------------------------------------------------------------------*/
 
-#include <stdio.h>
-
-#include "stratagus.h"
-
-#include "missile.h"
-
 #include "luacallback.h"
 #include "map.h"
+#include "missile.h"
 #include "unit.h"
 #include "unit_find.h"
 
+#include <cstdio>
+
 /**
 **  Handle tracer missile.
 **
diff --git a/src/network/net_lowlevel.cpp b/src/network/net_lowlevel.cpp
index 750938382a..06a5936aac 100644
--- a/src/network/net_lowlevel.cpp
+++ b/src/network/net_lowlevel.cpp
@@ -37,9 +37,9 @@
 
 #include "net_lowlevel.h"
 
-#include <stdio.h>
+#include <cerrno>
+#include <cstdio>
 #include <fcntl.h>
-#include <errno.h>
 
 //----------------------------------------------------------------------------
 //  Declarations
diff --git a/src/network/netsockets.cpp b/src/network/netsockets.cpp
index 9f2ef37fb0..8566b1ec2e 100644
--- a/src/network/netsockets.cpp
+++ b/src/network/netsockets.cpp
@@ -38,7 +38,7 @@
 #include "network/netsockets.h"
 #include "net_lowlevel.h"
 
-#include <stdio.h>
+#include <cstdio>
 
 //
 // CHost
diff --git a/src/network/network.cpp b/src/network/network.cpp
index 0cbcd0a41f..98e5607a14 100644
--- a/src/network/network.cpp
+++ b/src/network/network.cpp
@@ -222,9 +222,6 @@
 #include "online_service.h"
 #include "stratagus.h"
 
-#include <stddef.h>
-#include <list>
-
 #include "network.h"
 
 #include "actions.h"
@@ -244,7 +241,9 @@
 #include "unittype.h"
 #include "video.h"
 
+#include <cstddef>
 #include <deque>
+#include <list>
 
 //----------------------------------------------------------------------------
 //  Declaration
diff --git a/src/network/online_service.cpp b/src/network/online_service.cpp
index 2781cde1c1..26cf666db0 100644
--- a/src/network/online_service.cpp
+++ b/src/network/online_service.cpp
@@ -1981,7 +1981,7 @@ class C2S_SID_AUTH_INFO : public OnlineState
 		// Connect
 
 		std::string localHost = CNetworkParameter::Instance.localHost;
-		if (!localHost.compare("127.0.0.1")) {
+		if (localHost == "127.0.0.1") {
 			localHost = "0.0.0.0";
 		}
 		if (!ctx.getTCPSocket().IsValid()) {
@@ -2022,7 +2022,7 @@ class C2S_SID_AUTH_INFO : public OnlineState
 		// (UINT32) Language code
 		buffer.serialize32(0x00);
 		// (UINT32) Local IP
-		if (CNetworkParameter::Instance.localHost.compare("127.0.0.1")) {
+		if (CNetworkParameter::Instance.localHost != "127.0.0.1") {
 			// user set a custom local ip, use that
 #ifdef USE_WIN32
 			uint32_t addr = inet_addr(CNetworkParameter::Instance.localHost.c_str());
diff --git a/src/particle/chunkparticle.cpp b/src/particle/chunkparticle.cpp
index 6e13880490..045a183c8a 100644
--- a/src/particle/chunkparticle.cpp
+++ b/src/particle/chunkparticle.cpp
@@ -29,12 +29,11 @@
 
 //@{
 
-#include <math.h>
-
-#include "stratagus.h"
 #include "particle.h"
+#include "stratagus.h"
 #include "video.h"
 
+#include <cmath>
 
 static const int gravity = 32 * 12;
 
diff --git a/src/particle/radialparticle.cpp b/src/particle/radialparticle.cpp
index f0c0628752..948991b020 100644
--- a/src/particle/radialparticle.cpp
+++ b/src/particle/radialparticle.cpp
@@ -29,10 +29,10 @@
 
 //@{
 
-#include <math.h>
-
-#include "stratagus.h"
 #include "particle.h"
+#include "stratagus.h"
+
+#include <cmath>
 
 CRadialParticle::CRadialParticle(CPosition position, GraphicAnimation *animation, int maxSpeed, int drawlevel) :
 	CParticle(position, drawlevel)
diff --git a/src/pathfinder/astar.cpp b/src/pathfinder/astar.cpp
index 4c9f410d78..701caee3e0 100644
--- a/src/pathfinder/astar.cpp
+++ b/src/pathfinder/astar.cpp
@@ -60,7 +60,7 @@
 # include "viewport.h"
 #endif
 
-#include <stdio.h>
+#include <cstdio>
 
 /*----------------------------------------------------------------------------
 --  Declarations
diff --git a/src/stratagus/iolib.cpp b/src/stratagus/iolib.cpp
index a4b4c54014..c3a04b3608 100644
--- a/src/stratagus/iolib.cpp
+++ b/src/stratagus/iolib.cpp
@@ -45,10 +45,10 @@
 
 #include <SDL.h>
 
+#include <cstdarg>
+#include <cstdio>
 #include <map>
 #include <unordered_map>
-#include <stdarg.h>
-#include <stdio.h>
 
 #ifdef USE_ZLIB
 #include <zlib.h>
diff --git a/src/stratagus/parameters.cpp b/src/stratagus/parameters.cpp
index 267f493cf6..503e50a7da 100644
--- a/src/stratagus/parameters.cpp
+++ b/src/stratagus/parameters.cpp
@@ -34,7 +34,7 @@
 #include "filesystem.h"
 #include "parameters.h"
 
-#include <stdlib.h>
+#include <cstdlib>
 
 #ifdef USE_WIN32
 #include <Shlobj.h>
diff --git a/src/stratagus/stratagus.cpp b/src/stratagus/stratagus.cpp
index 6f3b78e23e..89a6ab2afc 100644
--- a/src/stratagus/stratagus.cpp
+++ b/src/stratagus/stratagus.cpp
@@ -164,7 +164,7 @@
 #pragma comment(lib, "Imm32.lib")
 #endif
 
-#include <ctype.h>
+#include <cctype>
 
 #ifdef USE_BEOS
 #include <fcntl.h>
@@ -221,8 +221,8 @@ extern void beos_init(int argc, char **argv);
 #include "st_backtrace.h"
 #endif
 
-#include <stdlib.h>
-#include <stdio.h>
+#include <cstdlib>
+#include <cstdio>
 
 #ifdef USE_WIN32
 # include <dbghelp.h>
diff --git a/src/stratagus/util.cpp b/src/stratagus/util.cpp
index 09f3a0fe8c..5b8dbebdf1 100644
--- a/src/stratagus/util.cpp
+++ b/src/stratagus/util.cpp
@@ -27,24 +27,18 @@
 //      02111-1307, USA.
 //
 
-#if __has_include(<charconv>)
-#include <charconv> // from_chars
-#endif
-
-#include <cstdint>
-#include <random>
+#include "util.h"
 
 #include "stratagus.h"
 
-#include "util.h"
-
 #include <SDL.h>
-
-#include <ctype.h>
-#include <errno.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <stdarg.h>
+#include <cctype>
+#include <cerrno>
+#include <cstdarg>
+#include <cstdint>
+#include <cstdio>
+#include <cstdlib>
+#include <random>
 #ifndef __APPLE__
 #include <malloc.h>
 #endif
@@ -61,6 +55,10 @@
 #include "st_backtrace.h"
 #endif
 
+#if __has_include(<charconv>)
+#include <charconv> // from_chars
+#endif
+
 /*----------------------------------------------------------------------------
 --  Random
 ----------------------------------------------------------------------------*/
@@ -342,7 +340,7 @@ int to_number(std::string_view s, int base)
 **  an 'argument required' error.
 */
 
-#include <string.h>
+#include <cstring>
 
 int opterr = 1;
 int optind = 1;
diff --git a/src/ui/botpanel.cpp b/src/ui/botpanel.cpp
index 08e9e49fc9..44e44632f8 100644
--- a/src/ui/botpanel.cpp
+++ b/src/ui/botpanel.cpp
@@ -56,7 +56,7 @@
 #include "upgrade.h"
 #include "video.h"
 
-#include <ctype.h>
+#include <cctype>
 #include <guichan/key.hpp>
 #include <guichan/sdl/sdlinput.hpp>
 #include <vector>
diff --git a/src/ui/button_checks.cpp b/src/ui/button_checks.cpp
index e1c4e4a618..ca8a7c4960 100644
--- a/src/ui/button_checks.cpp
+++ b/src/ui/button_checks.cpp
@@ -45,7 +45,8 @@
 #include "unittype.h"
 #include "upgrade.h"
 
-#include <stdio.h>
+#include <cstdio>
+
 /*----------------------------------------------------------------------------
 --  Functions
 ----------------------------------------------------------------------------*/
@@ -399,7 +400,7 @@ bool ButtonCheckSingleResearch(const CUnit &unit, const ButtonAction &button)
 */
 bool ButtonCheckDebug(const CUnit &, const ButtonAction &button)
 {
-	if(!button.AllowStr.compare("single-player-walls")) { /// Check if enabled walls for singleplayer games
+	if (button.AllowStr == "single-player-walls") { /// Check if enabled walls for singleplayer games
 		return !IsNetworkGame() && EnableWallsInSinglePlayer;
 	}
 	return false;
diff --git a/src/ui/mouse.cpp b/src/ui/mouse.cpp
index b47cbe5937..3f7b4c86a5 100644
--- a/src/ui/mouse.cpp
+++ b/src/ui/mouse.cpp
@@ -36,12 +36,6 @@
 --  Includes
 ----------------------------------------------------------------------------*/
 
-#include <ctype.h>
-#include <stdexcept>
-
-#include "stratagus.h"
-#include "ui.h"
-
 #include "action/action_build.h"
 #include "action/action_train.h"
 #include "actions.h"
@@ -57,7 +51,10 @@
 #include "player.h"
 #include "sound.h"
 #include "spells.h"
+#include "stratagus.h"
+#include "tileset.h"
 #include "translate.h"
+#include "ui.h"
 #include "unit.h"
 #include "unit_find.h"
 #include "unitsound.h"
@@ -65,9 +62,9 @@
 #include "video.h"
 #include "widgets.h"
 
-#include "tileset.h"
-
+#include <cctype>
 #include <guichan/actionevent.hpp>
+#include <stdexcept>
 
 /*----------------------------------------------------------------------------
 --  Variables
diff --git a/src/ui/ui.cpp b/src/ui/ui.cpp
index f792caf948..902c109f85 100644
--- a/src/ui/ui.cpp
+++ b/src/ui/ui.cpp
@@ -49,7 +49,7 @@
 #include "unit.h"
 #include "video.h"
 
-#include <stdarg.h>
+#include <cstdarg>
 
 /*----------------------------------------------------------------------------
 -- Variables
diff --git a/src/unit/build.cpp b/src/unit/build.cpp
index 4ae747e19c..cf029b4d8e 100644
--- a/src/unit/build.cpp
+++ b/src/unit/build.cpp
@@ -150,9 +150,9 @@ bool CBuildRestrictionDistance::Check(const CUnit *builder, const CUnitType &typ
 			(this->RestrictType == unit->Type || (!this->RestrictType && this->RestrictTypeOwner.size() > 0)) &&
 			// RestrictTypeOwner is not set or unit belongs to a suitable player
 			(this->RestrictTypeOwner.empty() ||
-			 (!this->RestrictTypeOwner.compare("self") && player == unit->Player) ||
-			 (!this->RestrictTypeOwner.compare("allied") && (player == unit->Player || player->IsAllied(*unit->Player))) ||
-			 (!this->RestrictTypeOwner.compare("enemy") && player->IsEnemy(*unit->Player)))) {
+			 (this->RestrictTypeOwner == "self" && player == unit->Player) ||
+			 (this->RestrictTypeOwner == "allied" && (player == unit->Player || player->IsAllied(*unit->Player))) ||
+			 (this->RestrictTypeOwner == "enemy" && player->IsEnemy(*unit->Player)))) {
 
 			switch (this->DistanceType) {
 				case EComparison::GreaterThan:
@@ -202,22 +202,22 @@ bool CBuildRestrictionHasUnit::Check(const CUnit *builder, const CUnitType &type
 	Vec2i pos2(0, 0);
 	CPlayer* player = builder != nullptr ? builder->Player : ThisPlayer;
 	int count = 0;
-	if (this->RestrictTypeOwner.size() == 0 || !this->RestrictTypeOwner.compare("self")) {
+	if (this->RestrictTypeOwner.empty() || this->RestrictTypeOwner == "self") {
 		count = player->GetUnitTotalCount(*this->RestrictType);
-	} else if (!this->RestrictTypeOwner.compare("allied")) {
+	} else if (this->RestrictTypeOwner == "allied") {
 		count = player->GetUnitTotalCount(*this->RestrictType);
 		for (int i = 0; i < NumPlayers; i++) {
 			if (player->IsAllied(Players[i])) {
 				count += Players[i].GetUnitTotalCount(*this->RestrictType);
 			}
 		}
-	} else if (!this->RestrictTypeOwner.compare("enemy")) {
+	} else if (this->RestrictTypeOwner == "enemy") {
 		for (int i = 0; i < NumPlayers; i++) {
 			if (player->IsEnemy(Players[i])) {
 				count += Players[i].GetUnitTotalCount(*this->RestrictType);
 			}
 		}
-	} else if (!this->RestrictTypeOwner.compare("any")) {
+	} else if (this->RestrictTypeOwner == "any") {
 		for (int i = 0; i < NumPlayers; i++) {
 			count += Players[i].GetUnitTotalCount(*this->RestrictType);
 		}
@@ -277,10 +277,10 @@ bool CBuildRestrictionSurroundedBy::Check(const CUnit *builder, const CUnitType
 			// unit has RestrictType or no RestrictType was set, but a RestrictTypeOwner
 			(this->RestrictType == unit->Type || (!this->RestrictType && this->RestrictTypeOwner.size() > 0)) &&
 			// RestrictTypeOwner is not set or unit belongs to a suitable player
-			(this->RestrictTypeOwner.size() == 0 ||
-				(!this->RestrictTypeOwner.compare("self") && builder->Player == unit->Player) ||
-				(!this->RestrictTypeOwner.compare("allied") && (builder->Player == unit->Player || builder->Player->IsAllied(*unit->Player))) ||
-				(!this->RestrictTypeOwner.compare("enemy") && builder->Player->IsEnemy(*unit->Player)))) {
+			(this->RestrictTypeOwner.empty() ||
+				(this->RestrictTypeOwner == "self" && builder->Player == unit->Player) ||
+				(this->RestrictTypeOwner == "allied" && (builder->Player == unit->Player || builder->Player->IsAllied(*unit->Player))) ||
+				(this->RestrictTypeOwner == "enemy" && builder->Player->IsEnemy(*unit->Player)))) {
 
 			switch (this->DistanceType) {
 				case EComparison::GreaterThan:
diff --git a/src/unit/unit.cpp b/src/unit/unit.cpp
index 950b9da2b8..4baccae999 100644
--- a/src/unit/unit.cpp
+++ b/src/unit/unit.cpp
@@ -66,8 +66,7 @@
 #include "upgrade.h"
 #include "video.h"
 
-#include <math.h>
-
+#include <cmath>
 
 /*----------------------------------------------------------------------------
 -- Documentation
diff --git a/src/unit/unit_find.cpp b/src/unit/unit_find.cpp
index b67bed2aa5..7d32590f9a 100644
--- a/src/unit/unit_find.cpp
+++ b/src/unit/unit_find.cpp
@@ -33,10 +33,6 @@
 --  Includes
 ----------------------------------------------------------------------------*/
 
-#include <limits.h>
-
-#include "stratagus.h"
-
 #include "unit_find.h"
 
 #include "actions.h"
@@ -50,6 +46,8 @@
 #include "unit_manager.h"
 #include "unittype.h"
 
+#include <climits>
+
 /*----------------------------------------------------------------------------
   -- Finding units
   ----------------------------------------------------------------------------*/
diff --git a/src/unit/unit_save.cpp b/src/unit/unit_save.cpp
index ae0a09ff77..e4b82c698f 100644
--- a/src/unit/unit_save.cpp
+++ b/src/unit/unit_save.cpp
@@ -49,7 +49,7 @@
 #include "spells.h"
 #include "unittype.h"
 
-#include <stdio.h>
+#include <cstdio>
 
 /*----------------------------------------------------------------------------
 --  Functions
diff --git a/src/unit/unittype.cpp b/src/unit/unittype.cpp
index 0b925c861a..94fdbac11e 100644
--- a/src/unit/unittype.cpp
+++ b/src/unit/unittype.cpp
@@ -33,8 +33,6 @@
 --  Includes
 ----------------------------------------------------------------------------*/
 
-#include "stratagus.h"
-
 #include "unittype.h"
 
 #include "animation.h"
@@ -56,11 +54,10 @@
 #include "util.h"
 #include "video.h"
 
+#include <cctype>
 #include <cmath>
-#include <ctype.h>
-
-#include <string>
 #include <map>
+#include <string>
 
 /*----------------------------------------------------------------------------
 -- Documentation
diff --git a/src/video/movie.cpp b/src/video/movie.cpp
index e1080c159e..ec5e6e5eef 100644
--- a/src/video/movie.cpp
+++ b/src/video/movie.cpp
@@ -509,12 +509,12 @@ SDL_Surface *Movie::getSurface() const /* override */
 
 #else
 
-#include <string>
-#include <string.h>
-#include <stdio.h>
-
 #include "stratagus.h"
 
+#include <string>
+#include <cstring>
+#include <cstdio>
+
 /**
 **  Play a video file.
 **
diff --git a/src/video/renderer.h b/src/video/renderer.h
index 1a2f47d794..052b93598c 100644
--- a/src/video/renderer.h
+++ b/src/video/renderer.h
@@ -1,7 +1,8 @@
 #ifndef __RENDERER_H__
 #define __RENDERER_H__
 
-#include <assert.h>
+#include <SDL.h>
+#include <cassert>
 
 struct CPrimitives {
 	virtual void DrawPixel(Uint32 color, int x, int y) = 0;
diff --git a/src/win32/SetupConsole_win32.cpp b/src/win32/SetupConsole_win32.cpp
index 66e5c8b78d..3bda7c6458 100644
--- a/src/win32/SetupConsole_win32.cpp
+++ b/src/win32/SetupConsole_win32.cpp
@@ -16,18 +16,23 @@
 
 */
 
+#include "SetupConsole_win32.h"
+
 #include <windows.h>
-#include <stdio.h>
+#include <cerrno>
+#include <cstdio>
 #include <io.h>
-#include <errno.h>
 #include <fcntl.h>
 
 #ifdef __cplusplus
-#include <iostream>
+# include <cerrno>
+# include <cstdio>
+# include <iostream>
+#else
+# include <errno.h>
+# include <stdio.h>
 #endif
 
-#include "SetupConsole_win32.h"
-
 /*
  * Microsoft systems were and always are one big mess where even standard output does not work :-(
  * There are at least 4 different I/O API levels and each WINAPI function initilize correctly just one...
diff --git a/tests/network/test_net_lowlevel.cpp b/tests/network/test_net_lowlevel.cpp
index 16bd34092b..d286d1cd83 100644
--- a/tests/network/test_net_lowlevel.cpp
+++ b/tests/network/test_net_lowlevel.cpp
@@ -31,7 +31,8 @@
 
 #include "stratagus.h"
 #include "net_lowlevel.h"
-#include <stdio.h>
+
+#include <cstdio>
 #include <thread>
 
 class AutoNetwork