diff --git a/include/colour.hpp b/include/colour.hpp
index 67ee15b2..4d02b80f 100644
--- a/include/colour.hpp
+++ b/include/colour.hpp
@@ -3,11 +3,15 @@
 
 // Helpers functions for converting colour channels between bit depths
 namespace Colour {
-    inline static u8 convert4To8Bit(u8 c) {
+    inline static constexpr u8 convert4To8Bit(u8 c) {
         return (c << 4) | c;
     }
 
-    inline static u8 convert5To8Bit(u8 c) {
+    inline static constexpr u8 convert5To8Bit(u8 c) {
         return (c << 3) | (c >> 2);
     }
+
+    inline static constexpr u8 convert6To8Bit(u8 c) {
+        return (c << 2) | (c >> 4);
+    }
 }
\ No newline at end of file