diff -r c2e0db52ea07 -r eae8b3bce545 src/linetypes/conditionaledge.cpp
--- a/src/linetypes/conditionaledge.cpp	Sun Mar 05 13:33:37 2017 +0200
+++ b/src/linetypes/conditionaledge.cpp	Sun Mar 05 16:47:52 2017 +0200
@@ -54,9 +54,13 @@
 {
 	LDEdgeLine* replacement = model()->emplaceReplacement<LDEdgeLine>(this);
 
-	for (int i = 0; i < replacement->numVertices(); ++i)
-		replacement->setVertex (i, vertex (i));
+	if (replacement)
+	{
+		for (int i = 0; i < replacement->numVertices(); ++i)
+			replacement->setVertex (i, vertex (i));
 
-	replacement->setColor (color());
+		replacement->setColor (color());
+	}
+
 	return replacement;
 }