diff --git a/source/platform/pconveyr.cpp b/source/platform/pconveyr.cpp
index fd1abb7b7..35195af8e 100644
--- a/source/platform/pconveyr.cpp
+++ b/source/platform/pconveyr.cpp
@@ -131,7 +131,7 @@ void CNpcConveyorPlatform::processMovement( int _frames )
 
 		s32 yPos = Pos.vy - offset.vy;
 
-		if ( yPos > VidGetScrH() )
+		if ( yPos < 0 || yPos > VidGetScrH() )
 		{
 			setToShutdown();
 		}
diff --git a/source/platform/pfallnor.cpp b/source/platform/pfallnor.cpp
index c932e1c9a..78bfeafc7 100644
--- a/source/platform/pfallnor.cpp
+++ b/source/platform/pfallnor.cpp
@@ -73,7 +73,7 @@ void CNpcFallingNoRespawnPlatform::processMovement( int _frames )
 
 		s32 yPos = Pos.vy - offset.vy;
 
-		if ( yPos > VidGetScrH() )
+		if ( yPos < 0 || yPos > VidGetScrH() )
 		{
 			setToShutdown();
 		}