diff --git a/docs/rh-log.txt b/docs/rh-log.txt
index 498f552d23..b1dd39e1e4 100644
--- a/docs/rh-log.txt
+++ b/docs/rh-log.txt
@@ -1,4 +1,5 @@
 June 11, 2008 (Changes by Graf Zahl)
+- Fixed: ACS's ChangeSky command didn't clean up the stack.
 - Fixed: Wall scrolling interpolations incremented their reference count twice.
 - Fixed: Before a level's thinkers are loaded all previous interpolations must
   be cleared.
diff --git a/src/p_acs.cpp b/src/p_acs.cpp
index 4c13739405..e46771afa8 100644
--- a/src/p_acs.cpp
+++ b/src/p_acs.cpp
@@ -5073,6 +5073,7 @@ int DLevelScript::RunScript ()
 					sky2texture = TexMan.GetTexture (sky2name, FTexture::TEX_Wall, FTextureManager::TEXMAN_Overridable|FTextureManager::TEXMAN_ReturnFirst);
 				}
 				R_InitSkyMap ();
+				sp -= 2;
 			}
 			break;