diff --git a/src/thingdef/thingdef_codeptr.cpp b/src/thingdef/thingdef_codeptr.cpp
index 8ca30621b..94aa922c0 100644
--- a/src/thingdef/thingdef_codeptr.cpp
+++ b/src/thingdef/thingdef_codeptr.cpp
@@ -3472,7 +3472,7 @@ DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_CheckLOF)
 		else return;
 
 		angle >>= ANGLETOFINESHIFT;
-		pitch = (0-pitch)>>ANGLETOFINESHIFT;
+		pitch >>= ANGLETOFINESHIFT;
 
 		vx = FixedMul (finecosine[pitch], finecosine[angle]);
 		vy = FixedMul (finecosine[pitch], finesine[angle]);
diff --git a/wadsrc/static/compatibility.txt b/wadsrc/static/compatibility.txt
index 478dffdc7..5aa7f82fd 100644
--- a/wadsrc/static/compatibility.txt
+++ b/wadsrc/static/compatibility.txt
@@ -397,6 +397,15 @@ A53AE580A4AF2B5D0B0893F86914781E // TNT: Evilution map31
 	setthingflags 470 2016
 }
 
+4CB7AAC5C43CF32BDF05FD36481C1D9F // Plutonia: Revisited map27
+{
+	setlinespecial 1214 Plat_DownWaitUpStayLip 20 64 150 0 0
+	setlinespecial 1215 Plat_DownWaitUpStayLip 20 64 150 0 0
+	setlinespecial 1216 Plat_DownWaitUpStayLip 20 64 150 0 0
+	setlinespecial 1217 Plat_DownWaitUpStayLip 20 64 150 0 0
+	setlinespecial 1227 Plat_DownWaitUpStayLip 20 64 150 0 0
+}
+
 D0139194F7817BF06F3988DFC47DB38D // Whispers of Satan map29
 {
 	nopassover