diff --git a/src/gui/dialogs/multiplayer/mp_login.cpp b/src/gui/dialogs/multiplayer/mp_login.cpp
index 60ed80c92fa4..07706cebd388 100644
--- a/src/gui/dialogs/multiplayer/mp_login.cpp
+++ b/src/gui/dialogs/multiplayer/mp_login.cpp
@@ -74,7 +74,7 @@ tmp_login::tmp_login(const std::string& label, const bool focus_password)
 	register_text("password",
 				  true,
 				  &preferences::password,
-				  NULL /* The password box returns '*' as value. */
+				  nullptr /* The password box returns '*' as value. */
 				  ,
 				  focus_password);
 
diff --git a/src/gui/widgets/multi_page.cpp b/src/gui/widgets/multi_page.cpp
index 336ba6fded4b..3f8a5b1adf73 100644
--- a/src/gui/widgets/multi_page.cpp
+++ b/src/gui/widgets/multi_page.cpp
@@ -42,14 +42,14 @@ tmulti_page::tmulti_page()
 void tmulti_page::add_page(const string_map& item)
 {
 	assert(generator_);
-	generator_->create_item(-1, page_builder_, item, NULL);
+	generator_->create_item(-1, page_builder_, item, nullptr);
 }
 
 void tmulti_page::add_page(
 		const std::map<std::string /* widget id */, string_map>& data)
 {
 	assert(generator_);
-	generator_->create_item(-1, page_builder_, data, NULL);
+	generator_->create_item(-1, page_builder_, data, nullptr);
 }
 
 void tmulti_page::remove_page(const unsigned page, unsigned count)
@@ -154,7 +154,7 @@ void swap_grid(tgrid* grid,
 void tmulti_page::finalize(const std::vector<string_map>& page_data)
 {
 	assert(generator_);
-	generator_->create_items(-1, page_builder_, page_data, NULL);
+	generator_->create_items(-1, page_builder_, page_data, nullptr);
 	swap_grid(nullptr, &grid(), generator_, "_content_grid");
 }
 
diff --git a/src/gui/widgets/stacked_widget.cpp b/src/gui/widgets/stacked_widget.cpp
index 227c20aa7ebf..4b4aa56de8a6 100644
--- a/src/gui/widgets/stacked_widget.cpp
+++ b/src/gui/widgets/stacked_widget.cpp
@@ -100,7 +100,7 @@ tstacked_widget::finalize(std::vector<tbuilder_grid_const_ptr> widget_builder)
 	string_map empty_data;
 	for(const auto & builder : widget_builder)
 	{
-		generator_->create_item(-1, builder, empty_data, NULL);
+		generator_->create_item(-1, builder, empty_data, nullptr);
 	}
 	swap_grid(nullptr, &grid(), generator_, "_content_grid");
 
diff --git a/src/gui/widgets/toggle_panel.cpp b/src/gui/widgets/toggle_panel.cpp
index f81f65494c64..c401e0456ce1 100644
--- a/src/gui/widgets/toggle_panel.cpp
+++ b/src/gui/widgets/toggle_panel.cpp
@@ -42,7 +42,7 @@ ttoggle_panel::ttoggle_panel()
 	, state_(ENABLED)
 	, state_num_(0)
 	, retval_(0)
-	, callback_state_change_(0)
+	, callback_state_change_(nullptr)
 	, callback_mouse_left_double_click_()
 {
 	set_wants_mouse_left_double_click();
diff --git a/src/intro.cpp b/src/intro.cpp
index 6dfd6ee53a0e..6d623c53e41e 100644
--- a/src/intro.cpp
+++ b/src/intro.cpp
@@ -53,7 +53,7 @@ void the_end(CVideo &video, std::string text, unsigned int duration)
 		if(n)
 			sdl::fill_rect(video.getSurface(),&area,0);
 
-		const SDL_Color col = create_color(n, n, n, n);
+		const SDL_Color col = create_color(uint8_t(n), uint8_t(n), uint8_t(n), uint8_t(n));
 		font::draw_text(&video,area,font_size,col,text,area.x,area.y);
 		update_rect(area);