diff --git a/Source/Plugins/BuilderModes/VisualModes/VisualVertexSlope.cs b/Source/Plugins/BuilderModes/VisualModes/VisualVertexSlope.cs
index 358eece0ab05fadea7315b7162c7fa43a9010c16..4764e88e24b110e3661b67d756fd0eabe1986351 100644
--- a/Source/Plugins/BuilderModes/VisualModes/VisualVertexSlope.cs
+++ b/Source/Plugins/BuilderModes/VisualModes/VisualVertexSlope.cs
@@ -213,6 +213,9 @@ namespace CodeImp.DoomBuilder.VisualModes
 					}
 			}
 
+			if (potentialhandles.Count == 0)
+				return null;
+
 			handle = potentialhandles.OrderByDescending(h => Vector2D.Distance(h.Vertex.Position, vertex.Position)).First();
 
 			if (handle == this)