diff --git a/language.version b/language.version
index 09c528d3f..a97df418e 100644
--- a/language.version
+++ b/language.version
@@ -1,3 +1,3 @@
 [default]
-SWWM_MODVER="\cyDEMOLITIONIST \cw1.3pre r741 \cu(Thu 19 Jan 10:09:20 CET 2023)\c-";
-SWWM_SHORTVER="\cw1.3pre r741 \cu(2023-01-19 10:09:20)\c-";
+SWWM_MODVER="\cyDEMOLITIONIST \cw1.3pre r742 \cu(Thu 19 Jan 10:23:20 CET 2023)\c-";
+SWWM_SHORTVER="\cw1.3pre r742 \cu(2023-01-19 10:23:20)\c-";
diff --git a/zscript/player/swwm_player_fx.zsc b/zscript/player/swwm_player_fx.zsc
index 2fe808b0d..74dee0ac2 100644
--- a/zscript/player/swwm_player_fx.zsc
+++ b/zscript/player/swwm_player_fx.zsc
@@ -73,9 +73,17 @@ Class SWWMMirrorTracer : LineTracer
 	{
 		if ( Results.HitType == TRACE_HitWall )
 		{
+			// did we find a mirror?
 			if ( !Results.HitLine.sidedef[1] && (Results.HitLine.special == Line_Mirror) )
 				return TRACE_Stop;
+			// lower/upper will block, as well as one-sided lines that aren't mirrors
+			if ( !Results.HitLine.sidedef[1] || !(Results.Tier == TIER_Middle) )
+				return TRACE_Abort;
 		}
+		// obviously, floors and ceilings block the view as well
+		// again, a shame we can't check if they, too, are mirrors
+		if ( (Results.HitType == TRACE_HitFloor) || (Results.HitType == TRACE_HitCeiling) )
+			return TRACE_Abort;
 		return TRACE_Skip;
 	}
 }