diff --git a/CMakeLists.txt b/CMakeLists.txt
index 13787cb2..90218e7a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -11,6 +11,11 @@ if(PSEMEK_BUILD_TYPE STREQUAL "DEBUG")
 	list(APPEND PSEMEK_DEFINITIONS "-DPSEMEK_DEBUG=1")
 endif()
 
+set(PSEMEK_CXX_FLAGS)
+if((CMAKE_CXX_COMPILER_ID STREQUAL "GNU") OR (CMAKE_CXX_COMPILER_ID STREQUAL "Clang"))
+	list(APPEND PSEMEK_CXX_FLAGS -Wall -Werror -Wextra -pedantic)
+endif()
+
 add_subdirectory(tools)
 add_subdirectory(libs)
 
diff --git a/libs/CMakeLists.txt b/libs/CMakeLists.txt
index 6ce71d8a..cfdf65e0 100644
--- a/libs/CMakeLists.txt
+++ b/libs/CMakeLists.txt
@@ -4,6 +4,7 @@ list(REMOVE_ITEM PSEMEK_LIBRARIES "CMakeLists.txt")
 foreach(lib ${PSEMEK_LIBRARIES})
 	add_subdirectory(${lib})
 	target_compile_definitions(${lib} PUBLIC ${PSEMEK_DEFINITIONS})
+	target_compile_options(${lib} PUBLIC ${PSEMEK_CXX_FLAGS})
 endforeach()
 
 set(PSEMEK_LIBRARIES ${PSEMEK_LIBRARIES} PARENT_SCOPE)
diff --git a/libs/app/include/psemek/app/scene.hpp b/libs/app/include/psemek/app/scene.hpp
index c65711b5..050e34e6 100644
--- a/libs/app/include/psemek/app/scene.hpp
+++ b/libs/app/include/psemek/app/scene.hpp
@@ -12,12 +12,12 @@ namespace psemek::app
 		virtual void on_scene_enter() {}
 		virtual void on_scene_exit() {}
 
-		virtual void on_resize(int width, int height) {}
+		virtual void on_resize(int /* width */, int /* height */) {}
 		virtual void on_focus_gained() {}
 		virtual void on_focus_lost() {}
 
-		virtual void on_mouse_move(int x, int y) {}
-		virtual void on_mouse_wheel(int delta) {}
+		virtual void on_mouse_move(int /* x */, int /* y */) {}
+		virtual void on_mouse_wheel(int /* delta */) {}
 		virtual void on_left_button_down() {}
 		virtual void on_left_button_up() {}
 		virtual void on_middle_button_down() {}
@@ -25,8 +25,8 @@ namespace psemek::app
 		virtual void on_right_button_down() {}
 		virtual void on_right_button_up() {}
 
-		virtual void on_key_down(SDL_Keycode key) {}
-		virtual void on_key_up(SDL_Keycode key) {}
+		virtual void on_key_down(SDL_Keycode /* key */) {}
+		virtual void on_key_up(SDL_Keycode /* key */) {}
 
 		virtual void update() {}
 		virtual void render() {}
diff --git a/libs/gfx/source/painter.cpp b/libs/gfx/source/painter.cpp
index eca1f83e..79639647 100644
--- a/libs/gfx/source/painter.cpp
+++ b/libs/gfx/source/painter.cpp
@@ -266,17 +266,17 @@ namespace psemek::gfx
 
 		for (char c : str)
 		{
-			if (c < 32 || c > 128) c = '?';
+			// Guard against unsigned char
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wtype-limits"
+			if ((c < 32) || (c >= 128)) c = '?';
+#pragma GCC diagnostic pop
 
 			int ty = (c - 32) / 16;
 			int tx = (c - 32) % 16;
 
 			std::uint32_t const base = impl().text_vertices.size();
 
-			geom::point<float, 2> position;
-			color_rgba color;
-			geom::point<std::uint16_t, 2> texcoord;
-
 			impl().text_vertices.push_back({pen, opts.c, to_texcoord(tx, ty)});
 			impl().text_vertices.push_back({pen + sx, opts.c, to_texcoord(tx + 1, ty)});
 			impl().text_vertices.push_back({pen + sy, opts.c, to_texcoord(tx, ty + 1)});
diff --git a/libs/log/include/psemek/log/log.hpp b/libs/log/include/psemek/log/log.hpp
index aca6ea1f..562cf3c4 100644
--- a/libs/log/include/psemek/log/log.hpp
+++ b/libs/log/include/psemek/log/log.hpp
@@ -9,7 +9,7 @@
 namespace psemek::log
 {
 
-	void set_max_thread_name_length(int length);
+	void set_max_thread_name_length(std::size_t length);
 
 	void register_thread(std::string name);
 	void register_thread(std::thread::id id, std::string name);
diff --git a/libs/log/source/log.cpp b/libs/log/source/log.cpp
index 46211246..a3f7cc14 100644
--- a/libs/log/source/log.cpp
+++ b/libs/log/source/log.cpp
@@ -12,9 +12,9 @@
 namespace psemek::log
 {
 
-	static int max_thread_name_length = 5;
+	static std::size_t max_thread_name_length = 5;
 
-	void set_max_thread_name_length(int length)
+	void set_max_thread_name_length(std::size_t length)
 	{
 		max_thread_name_length = length;
 	}
diff --git a/libs/pcg/source/blur.cpp b/libs/pcg/source/blur.cpp
index ea1fe88d..8c435625 100644
--- a/libs/pcg/source/blur.cpp
+++ b/libs/pcg/source/blur.cpp
@@ -27,9 +27,9 @@ namespace psemek::pcg
 
 		auto c = gauss_coeffs(size, sigma);
 
-		for (int y = 0; y < p.height(); ++y)
+		for (std::size_t y = 0; y < p.height(); ++y)
 		{
-			for (int x = 0; x < p.width(); ++x)
+			for (std::size_t x = 0; x < p.width(); ++x)
 			{
 				for (int j = - size; j <= size; ++j)
 				{
@@ -37,11 +37,11 @@ namespace psemek::pcg
 					{
 						int ix = (x + i);
 						while (ix < 0) ix += p.width();
-						if (ix >= p.width()) ix = ix % p.width();
+						if (static_cast<std::size_t>(ix) >= p.width()) ix = ix % p.width();
 
 						int iy = (y + j);
 						while (iy < 0) iy += p.height();
-						if (iy >= p.height()) iy = iy % p.height();
+						if (static_cast<std::size_t>(iy) >= p.height()) iy = iy % p.height();
 
 						res(x, y) += p(ix, iy) * c[i + size] * c[j + size];
 					}
diff --git a/libs/util/source/threadpool.cpp b/libs/util/source/threadpool.cpp
index ff69ce1b..ca6d46e9 100644
--- a/libs/util/source/threadpool.cpp
+++ b/libs/util/source/threadpool.cpp
@@ -1,4 +1,5 @@
 #include <psemek/util/threadpool.hpp>
+#include <psemek/util/unused.hpp>
 
 namespace psemek::util
 {
@@ -27,6 +28,7 @@ namespace psemek::util
 		tasks_queue.clear();
 		for (auto const & thread: threads)
 		{
+			unused(thread);
 			tasks_queue.push({});
 		}
 		threads.clear();