diff --git a/Half-Life.md b/Half-Life.md
index b10fca0..baa18a7 100644
--- a/Half-Life.md
+++ b/Half-Life.md
@@ -156,6 +156,12 @@ Used in Counter-Strike, Day of Defeat and Blue Shift of all things.
 
 Not even sources, I think community will figure out it themselves, but it needs VGUI2 SDK!
 
+## SDK: Licensing ambiguity
+
+The original Half-Life SDK license did not allow you to publish your source code changes. The GitHub doesn't state anything, but refers to the Source Engine SDK agreement - what is it Valve?
+
+Perhaps just make the SDK + engine headers free software at this point? It's not going to hurt!
+
 ## Inconsistency: Check HQ multiplayer models by default
 
 The 'Use high quality models' options under the multiplayer menu is never checked by default. If you're going to make the HD models the default, then the higher quality body groups for the multiplayer player models should be used as well.