diff --git a/wadsrc/static/compatibility.txt b/wadsrc/static/compatibility.txt
index bbf6abce6..1c9e5da14 100644
--- a/wadsrc/static/compatibility.txt
+++ b/wadsrc/static/compatibility.txt
@@ -488,6 +488,12 @@ F6EE16F770AD309D608EA0B1F1E249FC // Ultimate Doom, e4m3
 {
 	setsectorspecial 147 0
 }
+EBDAC00E9D25D884B2C8F4B1F0390539 // doom2.wad map21
+{
+   // push ceiling down in glitchy sectors above the stair switches
+   setsectoroffset 50 ceil -56
+   setsectoroffset 54 ceil -56
+}
 110F84DE041052B59307FAF0293E6BC0 // Doom II, map27
 {
 	setsectorspecial 93 0