diff --git a/lib/pathfinder/CPathfinder.cpp b/lib/pathfinder/CPathfinder.cpp
index 61cf7aa48..5430548f1 100644
--- a/lib/pathfinder/CPathfinder.cpp
+++ b/lib/pathfinder/CPathfinder.cpp
@@ -136,6 +136,9 @@ void CPathfinder::calculatePaths()
 			if(neighbour->locked)
 				continue;
 
+			if (source.node->theNodeBefore && source.node->theNodeBefore->coord == neighbour->coord )
+				continue; // block U-turns
+
 			if(!hlp->isLayerAvailable(neighbour->layer))
 				continue;