Index: src/common/engine/psworld.cpp
===================================================================
--- src/common/engine/psworld.cpp	(revision 5698)
+++ src/common/engine/psworld.cpp	(working copy)
@@ -151,7 +151,7 @@
         return true; // No need to transform, pos ok.
 
     int i = engine->GetSectors()->Find((iSector*)from);
-    if (i == -1)
+    if (i == csArrayItemNotFound || i > transarray.GetSize())
     {
         return false; // Didn't find transformation, pos not ok. 
     }
@@ -172,7 +172,7 @@
         return true;
 
     int i = engine->GetSectors()->Find((iSector*)from);
-    if (i == -1)
+    if (i == csArrayItemNotFound || i > transarray.GetSize())
         return false;
 
     csReversibleTransform* transform = transarray[i].Get((iSector*)to);