diff --git a/Global.h b/Global.h
index c1ee6ccb2..66f61d4d4 100644
--- a/Global.h
+++ b/Global.h
@@ -746,6 +746,12 @@ namespace vstd
 		}
 		return std::to_string(number) + *iter;
 	}
+	
+	///compile-time version of std::abs for ints for int3, in clang++15 std::abs is constexpr
+	static constexpr int abs(int i) {
+		if(i < 0) return -i;
+		return i;
+	}
 }
 using vstd::operator-=;
 
diff --git a/client/adventureMap/mapHandler.cpp b/client/adventureMap/mapHandler.cpp
index 70e02a41c..53c4f25e0 100644
--- a/client/adventureMap/mapHandler.cpp
+++ b/client/adventureMap/mapHandler.cpp
@@ -23,6 +23,7 @@
 #include "../../lib/mapObjects/CGHeroInstance.h"
 #include "../../lib/mapObjects/CObjectClassesHandler.h"
 #include "../../lib/mapping/CMap.h"
+#include "../../lib/Color.h"
 #include "../../lib/CConfigHandler.h"
 #include "../../lib/CGeneralTextHandler.h"
 #include "../../lib/CStopWatch.h"
@@ -925,21 +926,21 @@ void CMapHandler::CMapBlitter::blit(SDL_Surface * targetSurf, const MapDrawingIn
 		{
 			for (realPos.y = initPos.y, pos.y = topTile.y; pos.y < topTile.y + tileCount.y; pos.y++, realPos.y += tileSize)
 			{
-				const int3 color(0x555555, 0x555555, 0x555555);
+				constexpr ColorRGBA color(0x55, 0x55, 0x55);
 
 				if (realPos.y >= info->drawBounds.y &&
 					realPos.y < info->drawBounds.y + info->drawBounds.h)
 					for(int i = 0; i < tileSize; i++)
 						if (realPos.x + i >= info->drawBounds.x &&
 							realPos.x + i < info->drawBounds.x + info->drawBounds.w)
-							CSDL_Ext::putPixelWithoutRefresh(targetSurf, realPos.x + i, realPos.y, color.x, color.y, color.z);
+							CSDL_Ext::putPixelWithoutRefresh(targetSurf, realPos.x + i, realPos.y, color.r, color.g, color.b);
 
 				if (realPos.x >= info->drawBounds.x &&
 					realPos.x < info->drawBounds.x + info->drawBounds.w)
 					for(int i = 0; i < tileSize; i++)
 						if (realPos.y + i >= info->drawBounds.y &&
 							realPos.y + i < info->drawBounds.y + info->drawBounds.h)
-							CSDL_Ext::putPixelWithoutRefresh(targetSurf, realPos.x, realPos.y + i, color.x, color.y, color.z);
+							CSDL_Ext::putPixelWithoutRefresh(targetSurf, realPos.x, realPos.y + i, color.r, color.g, color.b);
 			}
 		}
 	}
diff --git a/client/windows/GUIClasses.cpp b/client/windows/GUIClasses.cpp
index f35a0d949..bc77d6be7 100644
--- a/client/windows/GUIClasses.cpp
+++ b/client/windows/GUIClasses.cpp
@@ -40,6 +40,7 @@
 #include "../lobby/CSavingScreen.h"
 #include "../renderSDL/SDL_Extensions.h"
 #include "../render/CAnimation.h"
+#include "../CMT.h"
 
 #include "../../CCallback.h"
 
diff --git a/lib/Color.h b/lib/Color.h
index f41f53d46..e6558e9f3 100644
--- a/lib/Color.h
+++ b/lib/Color.h
@@ -27,7 +27,7 @@ public:
 	uint8_t a;
 
 	//constructors
-	ColorRGBA()
+	constexpr ColorRGBA()
 		:r(0)
 		,g(0)
 		,b(0)
@@ -35,14 +35,14 @@ public:
 	{
 	}
 
-	ColorRGBA(uint8_t r, uint8_t g, uint8_t b, uint8_t a)
+	constexpr ColorRGBA(uint8_t r, uint8_t g, uint8_t b, uint8_t a)
 		: r(r)
 		, g(g)
 		, b(b)
 		, a(a)
 	{}
 
-	ColorRGBA(uint8_t r, uint8_t g, uint8_t b)
+	constexpr ColorRGBA(uint8_t r, uint8_t g, uint8_t b)
 		: r(r)
 		, g(g)
 		, b(b)
diff --git a/lib/ConstTransitivePtr.h b/lib/ConstTransitivePtr.h
index 3fccbc554..9867bf65e 100644
--- a/lib/ConstTransitivePtr.h
+++ b/lib/ConstTransitivePtr.h
@@ -16,7 +16,7 @@ VCMI_LIB_NAMESPACE_BEGIN
 template <typename T>
 class ConstTransitivePtr
 {
-	T *ptr;
+	T *ptr = nullptr;
 	ConstTransitivePtr(const T *Ptr)
 		: ptr(const_cast<T*>(Ptr)) 
 	{}
@@ -25,10 +25,7 @@ public:
 		: ptr(Ptr) 
 	{}
 	ConstTransitivePtr(std::nullptr_t)
-		: ptr(nullptr) 
 	{}
-
-
 	const T& operator*() const
 	{
 		return *ptr;
diff --git a/lib/int3.h b/lib/int3.h
index 73bda7d76..b665ff2db 100644
--- a/lib/int3.h
+++ b/lib/int3.h
@@ -18,48 +18,41 @@ public:
 	si32 x, y, z;
 
 	//c-tor: x, y, z initialized to 0
-	int3() : x(0), y(0), z(0) {} // I think that x, y, z should be left uninitialized.
+	constexpr int3() : x(0), y(0), z(0) {} // I think that x, y, z should be left uninitialized.
 	//c-tor: x, y, z initialized to i
-	explicit int3(const si32 i) : x(i), y(i), z(i) {}
+	explicit constexpr int3(const si32 i) : x(i), y(i), z(i) {}
 	//c-tor: x, y, z initialized to X, Y, Z
-	int3(const si32 X, const si32 Y, const si32 Z) : x(X), y(Y), z(Z) {}
-	int3(const int3 & c) : x(c.x), y(c.y), z(c.z) {} // Should be set to default (C++11)?
+	constexpr int3(const si32 X, const si32 Y, const si32 Z) : x(X), y(Y), z(Z) {}
+	constexpr int3(const int3 & c) = default;
 
-	int3 & operator=(const int3 & c) // Should be set to default (C++11)?
-	{
-		x = c.x;
-		y = c.y;
-		z = c.z;
+	constexpr int3 & operator=(const int3 & c) = default;
+	constexpr int3 operator-() const { return int3(-x, -y, -z); }
 
-		return *this;
-	}
-	int3 operator-() const { return int3(-x, -y, -z); }
-
-	int3 operator+(const int3 & i) const { return int3(x + i.x, y + i.y, z + i.z); }
-	int3 operator-(const int3 & i) const { return int3(x - i.x, y - i.y, z - i.z); }
+	constexpr int3 operator+(const int3 & i) const { return int3(x + i.x, y + i.y, z + i.z); }
+	constexpr int3 operator-(const int3 & i) const { return int3(x - i.x, y - i.y, z - i.z); }
 	//returns int3 with coordinates increased by given number
-	int3 operator+(const si32 i) const { return int3(x + i, y + i, z + i); }
+	constexpr int3 operator+(const si32 i) const { return int3(x + i, y + i, z + i); }
 	//returns int3 with coordinates decreased by given number
-	int3 operator-(const si32 i) const { return int3(x - i, y - i, z - i); }
+	constexpr int3 operator-(const si32 i) const { return int3(x - i, y - i, z - i); }
 
 	//returns int3 with coordinates multiplied by given number
-	int3 operator*(const double i) const { return int3((int)(x * i), (int)(y * i), (int)(z * i)); }
+	constexpr int3 operator*(const double i) const { return int3((int)(x * i), (int)(y * i), (int)(z * i)); }
 	//returns int3 with coordinates divided by given number
-	int3 operator/(const double i) const { return int3((int)(x / i), (int)(y / i), (int)(z / i)); }
+	constexpr int3 operator/(const double i) const { return int3((int)(x / i), (int)(y / i), (int)(z / i)); }
 
 	//returns int3 with coordinates multiplied by given number
-	int3 operator*(const si32 i) const { return int3(x * i, y * i, z * i); }
+	constexpr int3 operator*(const si32 i) const { return int3(x * i, y * i, z * i); }
 	//returns int3 with coordinates divided by given number
-	int3 operator/(const si32 i) const { return int3(x / i, y / i, z / i); }
+	constexpr int3 operator/(const si32 i) const { return int3(x / i, y / i, z / i); }
 
-	int3 & operator+=(const int3 & i)
+	constexpr int3 & operator+=(const int3 & i)
 	{
 		x += i.x;
 		y += i.y;
 		z += i.z;
 		return *this;
 	}
-	int3 & operator-=(const int3 & i)
+	constexpr int3 & operator-=(const int3 & i)
 	{
 		x -= i.x;
 		y -= i.y;
@@ -68,7 +61,7 @@ public:
 	}
 
 	//increases all coordinates by given number
-	int3 & operator+=(const si32 i)
+	constexpr int3 & operator+=(const si32 i)
 	{
 		x += i;
 		y += i;
@@ -76,7 +69,7 @@ public:
 		return *this;
 	}
 	//decreases all coordinates by given number
-	int3 & operator-=(const si32 i)
+	constexpr int3 & operator-=(const si32 i)
 	{
 		x -= i;
 		y -= i;
@@ -84,10 +77,10 @@ public:
 		return *this;
 	}
 
-	bool operator==(const int3 & i) const { return (x == i.x && y == i.y && z == i.z); }
-	bool operator!=(const int3 & i) const { return (x != i.x || y != i.y || z != i.z); }
+	constexpr bool operator==(const int3 & i) const { return (x == i.x && y == i.y && z == i.z); }
+	constexpr bool operator!=(const int3 & i) const { return (x != i.x || y != i.y || z != i.z); }
 
-	bool operator<(const int3 & i) const
+	constexpr bool operator<(const int3 & i) const
 	{
 		if (z < i.z)
 			return true;
@@ -130,7 +123,7 @@ public:
 	}
 
 	//returns squared distance on Oxy plane (z coord is not used)
-	ui32 dist2dSQ(const int3 & o) const
+	constexpr ui32 dist2dSQ(const int3 & o) const
 	{
 		const si32 dx = (x - o.x);
 		const si32 dy = (y - o.y);
@@ -142,17 +135,17 @@ public:
 		return std::sqrt((double)dist2dSQ(o));
 	}
 	//manhattan distance used for patrol radius (z coord is not used)
-	double mandist2d(const int3 & o) const
+	constexpr double mandist2d(const int3 & o) const
 	{
-		return abs(o.x - x) + abs(o.y - y);
+		return vstd::abs(o.x - x) + vstd::abs(o.y - y);
 	}
 	//chebyshev distance used for ambient sounds (z coord is not used)
-	double chebdist2d(const int3 & o) const
+	constexpr double chebdist2d(const int3 & o) const
 	{
-		return std::max(std::abs(o.x - x), std::abs(o.y - y));
+		return std::max(vstd::abs(o.x - x), vstd::abs(o.y - y));
 	}
 
-	bool areNeighbours(const int3 & o) const
+	constexpr bool areNeighbours(const int3 & o) const
 	{
 		return (dist2dSQ(o) < 4) && (z == o.z);
 	}
@@ -169,7 +162,7 @@ public:
 		return result;
 	}
 
-	bool valid() const //Should be named "isValid"?
+	constexpr bool valid() const //Should be named "isValid"?
 	{
 		return z >= 0; //minimal condition that needs to be fulfilled for tiles in the map
 	}
@@ -182,7 +175,7 @@ public:
 		h & z;
 	}
 
-	static std::array<int3, 8> getDirs()
+	constexpr static std::array<int3, 8> getDirs()
 	{
 		return { { int3(0,1,0),int3(0,-1,0),int3(-1,0,0),int3(+1,0,0),
 			int3(1,1,0),int3(-1,1,0),int3(1,-1,0),int3(-1,-1,0) } };
diff --git a/lib/rmg/ObjectManager.cpp b/lib/rmg/ObjectManager.cpp
index feb58fda7..a249bef9c 100644
--- a/lib/rmg/ObjectManager.cpp
+++ b/lib/rmg/ObjectManager.cpp
@@ -241,7 +241,6 @@ bool ObjectManager::createRequiredObjects()
 	for(const auto & object : requiredObjects)
 	{
 		auto * obj = object.first;
-		int3 pos;
 		rmg::Object rmgObject(*obj);
 		rmgObject.setTemplate(zone.getTerrainType());
 		bool guarded = addGuard(rmgObject, object.second, (obj->ID == Obj::MONOLITH_TWO_WAY));
@@ -278,7 +277,6 @@ bool ObjectManager::createRequiredObjects()
 	for(const auto & object : closeObjects)
 	{
 		auto * obj = object.first;
-		int3 pos;
 		auto possibleArea = zone.areaPossible();
 		rmg::Object rmgObject(*obj);
 		rmgObject.setTemplate(zone.getTerrainType());
diff --git a/lib/rmg/TreasurePlacer.cpp b/lib/rmg/TreasurePlacer.cpp
index 66bfe792e..a076a56eb 100644
--- a/lib/rmg/TreasurePlacer.cpp
+++ b/lib/rmg/TreasurePlacer.cpp
@@ -736,7 +736,6 @@ void TreasurePlacer::createTreasures(ObjectManager & manager)
 			if(guarded)
 				guarded = manager.addGuard(rmgObject, value);
 			
-			int3 pos;
 			auto possibleArea = zone.areaPossible();
 			
 			auto path = rmg::Path::invalid();