diff --git a/wadsrc/static/compatibility.txt b/wadsrc/static/compatibility.txt
index 795c7f0b0..1a115fbe8 100644
--- a/wadsrc/static/compatibility.txt
+++ b/wadsrc/static/compatibility.txt
@@ -340,3 +340,12 @@ F481922F4881F74760F3C0437FD5EDD0 // map03
 	rebuildnodes
 }
 
+1891E029994B023910CFE0B3209C3CDB // Ultimate Simplicity, map07
+{
+	// It is possible to get stuck on skill 0 or 1 when no shots have been fired
+	// after sector 17 became accessible and before entering famous mancubus room.
+	// Monsters from the mentioned sector won't be alerted and so 
+	// they won't teleport into the battle. ACS will wait forever for their deaths.
+	setlinespecial 397 NoiseAlert 0 0 0 0 0
+	setlinespecial 411 NoiseAlert 0 0 0 0 0
+}