diff --git a/src/p_map.c b/src/p_map.c
index 8227e6225..3aaf7d78b 100644
--- a/src/p_map.c
+++ b/src/p_map.c
@@ -1879,6 +1879,8 @@ boolean P_CheckPosition(mobj_t *thing, fixed_t x, fixed_t y, TryMoveResult_t *re
 		}
 	}
 
+	P_ClearTestLines();
+
 	// The bounding box is extended by MAXRADIUS
 	// because mobj_ts are grouped into mapblocks
 	// based on their origin point, and can overlap
@@ -2008,8 +2010,6 @@ boolean P_CheckPosition(mobj_t *thing, fixed_t x, fixed_t y, TryMoveResult_t *re
 
 	validcount++;
 
-	P_ClearTestLines();
-
 	// check lines
 	for (bx = xl; bx <= xh; bx++)
 	{
diff --git a/src/p_polyobj.c b/src/p_polyobj.c
index da7aad6bb..f8e389c8d 100644
--- a/src/p_polyobj.c
+++ b/src/p_polyobj.c
@@ -200,6 +200,10 @@ boolean P_BBoxInsidePolyobj(polyobj_t *po, fixed_t *bbox)
 	{
 		if (P_BoxOnLineSide(bbox, po->lines[i]) == 0)
 			return false;
+		if (tm.sweep)
+		{
+			P_TestLine(po->lines[i]);
+		}
 	}
 
 	return true;