--- src/video/SDL_surface.c.orig	2017-09-12 22:40:34.696199701 +0200
+++ src/video/SDL_surface.c	2017-09-13 23:18:16.939879983 +0200
@@ -988,31 +988,43 @@
         }
 
         if (set_colorkey_by_color) {
-            SDL_Surface *tmp;
-            SDL_Surface *tmp2;
-            int converted_colorkey = 0;
+            if (surface->format->BitsPerPixel == 16) {
+                /* 16-bit "565 format" surfaces need special handling */
 
-            /* Create a dummy surface to get the colorkey converted */
-            tmp = SDL_CreateRGBSurface(0, 1, 1,
-                                   surface->format->BitsPerPixel, surface->format->Rmask,
-                                   surface->format->Gmask, surface->format->Bmask,
-                                   surface->format->Amask);
-
-            SDL_FillRect(tmp, NULL, surface->map->info.colorkey);
-
-            tmp->map->info.flags &= ~SDL_COPY_COLORKEY;
-
-            /* Convertion of the colorkey */
-            tmp2 = SDL_ConvertSurface(tmp, format, 0);
-
-            /* Get the converted colorkey */
-            SDL_memcpy(&converted_colorkey, tmp2->pixels, tmp2->format->BytesPerPixel);
-
-            SDL_FreeSurface(tmp);
-            SDL_FreeSurface(tmp2);
-
-            /* Set the converted colorkey on the new surface */
-            SDL_SetColorKey(convert, 1, converted_colorkey);
+                SDL_Surface *tmp;
+                SDL_Surface *tmp2;
+                int converted_colorkey = 0;
+
+                /* Create a dummy surface to get the colorkey converted */
+                tmp = SDL_CreateRGBSurface(0, 1, 1,
+                                       surface->format->BitsPerPixel, surface->format->Rmask,
+                                       surface->format->Gmask, surface->format->Bmask,
+                                       surface->format->Amask);
+
+                SDL_FillRect(tmp, NULL, surface->map->info.colorkey);
+
+                tmp->map->info.flags &= ~SDL_COPY_COLORKEY;
+
+                /* Convertion of the colorkey */
+                tmp2 = SDL_ConvertSurface(tmp, format, 0);
+
+                /* Get the converted colorkey */
+                SDL_memcpy(&converted_colorkey, tmp2->pixels, tmp2->format->BytesPerPixel);
+
+                SDL_FreeSurface(tmp);
+                SDL_FreeSurface(tmp2);
+
+                /* Set the converted colorkey on the new surface */
+                SDL_SetColorKey(convert, 1, converted_colorkey);
+            } else {
+              /* Set the colorkey by color, which needs to be unique */
+              Uint8 keyR, keyG, keyB, keyA;
+
+              SDL_GetRGBA(surface->map->info.colorkey, surface->format, &keyR,
+                          &keyG, &keyB, &keyA);
+              SDL_SetColorKey(convert, 1,
+                              SDL_MapRGBA(convert->format, keyR, keyG, keyB, keyA));
+            }
 
             /* This is needed when converting for 3D texture upload */
             SDL_ConvertColorkeyToAlpha(convert);