diff --git a/src/display.cpp b/src/display.cpp
index 6f397159077..8c453daf97a 100644
--- a/src/display.cpp
+++ b/src/display.cpp
@@ -19,6 +19,7 @@
  */
 
 #include "arrow.hpp"
+#include "color.hpp"
 #include "cursor.hpp"
 #include "display.hpp"
 #include "draw.hpp"
@@ -28,6 +29,7 @@
 #include "font/text.hpp"
 #include "preferences/game.hpp"
 #include "gettext.hpp"
+#include "gui/dialogs/loading_screen.hpp"
 #include "halo.hpp"
 #include "hotkey/command_executor.hpp"
 #include "language.hpp"
@@ -39,7 +41,8 @@
 #include "play_controller.hpp" //note: this can probably be refactored out
 #include "reports.hpp"
 #include "resources.hpp"
-#include "color.hpp"
+#include "sdl/utils.hpp" // fill_surface_rect
+#include "show_dialog.hpp"
 #include "synced_context.hpp"
 #include "team.hpp"
 #include "terrain/builder.hpp"
@@ -51,8 +54,6 @@
 #include "units/drawer.hpp"
 #include "units/orb_status.hpp"
 #include "whiteboard/manager.hpp"
-#include "show_dialog.hpp"
-#include "gui/dialogs/loading_screen.hpp"
 
 #include <SDL2/SDL_image.h>
 
diff --git a/src/display.hpp b/src/display.hpp
index 738471e47c2..0fddca1b0eb 100644
--- a/src/display.hpp
+++ b/src/display.hpp
@@ -849,7 +849,7 @@ public:
 	void render_image(int x, int y, const display::drawing_layer drawing_layer,
 			const map_location& loc, const image::locator& i_locator,
 			bool hreverse=false, bool greyscale=false,
-			int32_t alpha=floating_to_fixed_point(1.0), color_t blendto = {0,0,0},
+			int32_t alpha=SDL_ALPHA_OPAQUE, color_t blendto = {0,0,0},
 			double blend_ratio=0, double submerged=0.0,bool vreverse =false);
 
 	/**
diff --git a/src/draw.cpp b/src/draw.cpp
index 8798cb7cdc4..32fe4f05fa8 100644
--- a/src/draw.cpp
+++ b/src/draw.cpp
@@ -19,6 +19,7 @@
 #include "sdl/rect.hpp"
 #include "sdl/surface.hpp"
 #include "sdl/texture.hpp"
+#include "sdl/utils.hpp" // sdl::runtime_at_least
 #include "video.hpp"
 
 #include <SDL2/SDL_rect.h>
diff --git a/src/floating_label.cpp b/src/floating_label.cpp
index 4b063323955..44423932eff 100644
--- a/src/floating_label.cpp
+++ b/src/floating_label.cpp
@@ -19,6 +19,7 @@
 #include "draw.hpp"
 #include "font/text.hpp"
 #include "log.hpp"
+#include "sdl/utils.hpp"
 #include "video.hpp"
 
 #include <map>
diff --git a/src/game_display.cpp b/src/game_display.cpp
index 3c894ec2716..6eefc35cd0c 100644
--- a/src/game_display.cpp
+++ b/src/game_display.cpp
@@ -37,6 +37,7 @@
 #include "font/standard_colors.hpp"
 #include "reports.hpp"
 #include "resources.hpp"
+#include "sdl/utils.hpp"
 #include "tod_manager.hpp"
 #include "color.hpp"
 #include "synced_context.hpp"
diff --git a/src/gui/core/canvas.cpp b/src/gui/core/canvas.cpp
index eea8fca2b7f..e7dce31ef9e 100644
--- a/src/gui/core/canvas.cpp
+++ b/src/gui/core/canvas.cpp
@@ -34,6 +34,7 @@
 #include "sdl/point.hpp"
 #include "sdl/rect.hpp"
 #include "sdl/texture.hpp"
+#include "sdl/utils.hpp" // blur_surface
 #include "video.hpp"
 #include "wml_exception.hpp"
 
diff --git a/src/gui/dialogs/campaign_difficulty.cpp b/src/gui/dialogs/campaign_difficulty.cpp
index b24938f9702..627455a6126 100644
--- a/src/gui/dialogs/campaign_difficulty.cpp
+++ b/src/gui/dialogs/campaign_difficulty.cpp
@@ -18,15 +18,16 @@
 #include "gui/dialogs/campaign_difficulty.hpp"
 
 #include "config.hpp"
+#include "deprecation.hpp"
 #include "font/text_formatting.hpp"
 #include "formatter.hpp"
+#include "game_version.hpp"
 #include "gui/auxiliary/find_widget.hpp"
-#include "preferences/game.hpp"
 #include "gui/widgets/listbox.hpp"
 #include "gui/widgets/window.hpp"
 #include "log.hpp"
+#include "preferences/game.hpp"
 #include "serialization/string_utils.hpp"
-#include "deprecation.hpp"
 
 static lg::log_domain log_wml("wml");
 #define WRN_WML LOG_STREAM(warn, log_wml)
diff --git a/src/gui/widgets/slider.cpp b/src/gui/widgets/slider.cpp
index 6eabe4d59b9..3853b99a099 100644
--- a/src/gui/widgets/slider.cpp
+++ b/src/gui/widgets/slider.cpp
@@ -27,6 +27,7 @@
 #include "sdl/rect.hpp"
 #include "sound.hpp"
 #include "gettext.hpp"
+#include "utils/math.hpp"
 #include "wml_exception.hpp"
 
 #include <functional>
diff --git a/src/minimap.cpp b/src/minimap.cpp
index a5d08ec6c50..d8b453e4e8a 100644
--- a/src/minimap.cpp
+++ b/src/minimap.cpp
@@ -28,6 +28,7 @@
 #include "preferences/general.hpp"
 #include "resources.hpp"
 #include "sdl/surface.hpp"
+#include "sdl/utils.hpp"
 #include "team.hpp"
 #include "terrain/type_data.hpp"
 #include "units/unit.hpp"
diff --git a/src/sdl/rect.cpp b/src/sdl/rect.cpp
index e70194a9a80..6ebc2a540f7 100644
--- a/src/sdl/rect.cpp
+++ b/src/sdl/rect.cpp
@@ -18,6 +18,8 @@
 #include "sdl/window.hpp"
 #include "video.hpp"
 
+#include <iostream>
+
 namespace sdl
 {
 bool point_in_rect(int x, int y, const SDL_Rect& rect)
diff --git a/src/sdl/rect.hpp b/src/sdl/rect.hpp
index e07fbc1769c..f1a307d9ac4 100644
--- a/src/sdl/rect.hpp
+++ b/src/sdl/rect.hpp
@@ -20,12 +20,10 @@
  * Contains the SDL_Rect helper code.
  */
 
-#include "utils.hpp"
+#include "sdl/point.hpp"
 
 #include <SDL2/SDL_rect.h>
 
-struct point;
-
 namespace sdl
 {
 
@@ -89,18 +87,6 @@ SDL_Rect intersect_rects(const SDL_Rect& rect1, const SDL_Rect& rect2);
  */
 SDL_Rect union_rects(const SDL_Rect &rect1, const SDL_Rect &rect2);
 
-/**
- * Fill a rectangle on a given surface. Alias for SDL_FillRect.
- *
- * @param dst                     The surface to operate on.
- * @param dst_rect                The rectangle to fill.
- * @param color                   Color of the rectangle.
- */
-inline void fill_surface_rect(surface& dst, SDL_Rect* dst_rect, const uint32_t color)
-{
-	SDL_FillRect(dst, dst_rect, color);
-}
-
 } // namespace sdl
 
 bool operator==(const SDL_Rect& a, const SDL_Rect& b);
diff --git a/src/sdl/surface.cpp b/src/sdl/surface.cpp
index 0caf0337d19..f2c07b72777 100644
--- a/src/sdl/surface.cpp
+++ b/src/sdl/surface.cpp
@@ -14,6 +14,7 @@
 
 #include "sdl/surface.hpp"
 
+#include "color.hpp"
 #include "draw.hpp" // for surface_restorer. Remove that then remove this.
 #include "sdl/rect.hpp"
 #include "video.hpp" // for surface_restorer. Remove that then remove this.
diff --git a/src/sdl/utils.hpp b/src/sdl/utils.hpp
index fa444de0850..96487e44db3 100644
--- a/src/sdl/utils.hpp
+++ b/src/sdl/utils.hpp
@@ -39,6 +39,18 @@ version_info get_version();
  */
 bool runtime_at_least(uint8_t major, uint8_t minor = 0, uint8_t patch = 0);
 
+/**
+ * Fill a rectangle on a given surface. Alias for SDL_FillRect.
+ *
+ * @param dst                     The surface to operate on.
+ * @param dst_rect                The rectangle to fill.
+ * @param color                   Color of the rectangle.
+ */
+inline void fill_surface_rect(surface& dst, SDL_Rect* dst_rect, const uint32_t color)
+{
+	SDL_FillRect(dst, dst_rect, color);
+}
+
 } // namespace sdl
 
 
diff --git a/src/show_dialog.cpp b/src/show_dialog.cpp
index e830652509e..30204a050b3 100644
--- a/src/show_dialog.cpp
+++ b/src/show_dialog.cpp
@@ -29,6 +29,7 @@
 #include "font/standard_colors.hpp"
 #include "sdl/rect.hpp"
 #include "sdl/input.hpp" // get_mouse_state
+#include "sdl/utils.hpp" // blur_surface
 
 static lg::log_domain log_display("display");
 #define ERR_DP LOG_STREAM(err, log_display)
diff --git a/src/units/drawer.cpp b/src/units/drawer.cpp
index f66bb1592d0..ad36d0e8d34 100644
--- a/src/units/drawer.cpp
+++ b/src/units/drawer.cpp
@@ -26,6 +26,7 @@
 #include "picture.hpp"
 #include "preferences/game.hpp"
 #include "sdl/surface.hpp"
+#include "sdl/utils.hpp" // scale_surface_nn, fill_surface_rect
 #include "team.hpp"
 #include "units/animation.hpp"
 #include "units/animation_component.hpp"
diff --git a/src/units/frame.cpp b/src/units/frame.cpp
index e9149e4388d..521be8ebd07 100644
--- a/src/units/frame.cpp
+++ b/src/units/frame.cpp
@@ -18,6 +18,7 @@
 #include "color.hpp"
 #include "game_display.hpp"
 #include "log.hpp"
+#include "sdl/utils.hpp" // floating_to_fixed_point
 #include "sound.hpp"
 
 static lg::log_domain log_engine("engine");