diff --git a/backends/imgui_impl_opengl3.h b/backends/imgui_impl_opengl3.h
index 98c9aca1..19f185b8 100644
--- a/backends/imgui_impl_opengl3.h
+++ b/backends/imgui_impl_opengl3.h
@@ -46,7 +46,7 @@ IMGUI_IMPL_API void     ImGui_ImplOpenGL3_DestroyDeviceObjects();
 #endif
 #if (defined(__APPLE__) && (TARGET_OS_IOS || TARGET_OS_TV)) || (defined(__ANDROID__))
 #define IMGUI_IMPL_OPENGL_ES3               // iOS, Android  -> GL ES 3, "#version 300 es"
-#elif defined(__EMSCRIPTEN__)
+#elif defined(__EMSCRIPTEN__) || defined(__amigaos4__)
 #define IMGUI_IMPL_OPENGL_ES2               // Emscripten    -> GL ES 2, "#version 100"
 #else
 // Otherwise imgui_impl_opengl3_loader.h will be used.
diff --git a/backends/imgui_impl_sdl.cpp b/backends/imgui_impl_sdl.cpp
index bed000be..5a52fc67 100644
--- a/backends/imgui_impl_sdl.cpp
+++ b/backends/imgui_impl_sdl.cpp
@@ -70,7 +70,7 @@
 #include <TargetConditionals.h>
 #endif
 
-#if SDL_VERSION_ATLEAST(2,0,4) && !defined(__EMSCRIPTEN__) && !defined(__ANDROID__) && !(defined(__APPLE__) && TARGET_OS_IOS)
+#if SDL_VERSION_ATLEAST(2,0,4) && !defined(__EMSCRIPTEN__) && !defined(__ANDROID__) && !(defined(__APPLE__) && TARGET_OS_IOS) && !defined(__amigaos4__)
 #define SDL_HAS_CAPTURE_AND_GLOBAL_MOUSE    1
 #else
 #define SDL_HAS_CAPTURE_AND_GLOBAL_MOUSE    0
diff --git a/docs/CHANGELOG.txt b/docs/CHANGELOG.txt
index dedad70e..1503ec26 100644
--- a/docs/CHANGELOG.txt
+++ b/docs/CHANGELOG.txt
@@ -79,6 +79,7 @@ Other Changes:
 - Misc: Fixed calling GetID("label") _before_ a widget emitting this item inside a group (such as InputInt())
   from causing an assertion when closing the group. (#5181).
 - Misc: Fixed IsAnyItemHovered() returning false when using navigation.
+- Misc: Allow redefining IM_COL32_XXX layout macros to facilitate use on big-endian systems. (#5190, #767, #844)
 - Misc: Added IMGUI_STB_SPRINTF_FILENAME to support custom path to stb_sprintf. (#5068, #2954) [@jakubtomsu]
 - Misc: Added constexpr to ImVec2/ImVec4 inline constructors. (#4995) [@Myriachan]
 - Misc: Updated stb_truetype.h from 1.20 to 1.26 (many fixes). (#5075)
@@ -90,6 +91,7 @@ Other Changes:
   reported incorrectly on Linux/X11, due to a bug in GLFW. [@rokups]
 - Backends: SDL: Fixed dragging out viewport broken on some SDL setups. (#5012) [@rokups]
 - Backends: SDL: Added support for extra mouse buttons (SDL_BUTTON_X1/SDL_BUTTON_X2). (#5125) [@sgiurgiu]
+- Backends: SDL, OpenGL3: Fixes to facilitate building on AmigaOS4. (#5190) [@afxgroup]
 - Backends: OSX: Monitor NSKeyUp events to catch missing keyUp for key when user press Cmd + key (#5128) [@thedmd]
 - Examples: Emscripten: Fix building for latest Emscripten specs. (#3632)
 
diff --git a/imgui.h b/imgui.h
index 9cc21e5a..77ab3ec4 100644
--- a/imgui.h
+++ b/imgui.h
@@ -2316,6 +2316,8 @@ struct ImGuiListClipper
 };
 
 // Helpers macros to generate 32-bit encoded colors
+// User can declare their own format by #defining the 5 _SHIFT/_MASK macros in their imconfig file.
+#ifndef IM_COL32_R_SHIFT
 #ifdef IMGUI_USE_BGRA_PACKED_COLOR
 #define IM_COL32_R_SHIFT    16
 #define IM_COL32_G_SHIFT    8
@@ -2329,6 +2331,7 @@ struct ImGuiListClipper
 #define IM_COL32_A_SHIFT    24
 #define IM_COL32_A_MASK     0xFF000000
 #endif
+#endif
 #define IM_COL32(R,G,B,A)    (((ImU32)(A)<<IM_COL32_A_SHIFT) | ((ImU32)(B)<<IM_COL32_B_SHIFT) | ((ImU32)(G)<<IM_COL32_G_SHIFT) | ((ImU32)(R)<<IM_COL32_R_SHIFT))
 #define IM_COL32_WHITE       IM_COL32(255,255,255,255)  // Opaque white = 0xFFFFFFFF
 #define IM_COL32_BLACK       IM_COL32(0,0,0,255)        // Opaque black