diff --git a/Trajectories/Tests/tests.json b/Trajectories/Tests/tests.json
index bab58e5cfa78a5dbbc250f9f3c7162d169091851..a6d147e91cae9776b1bed4aeab6a742029f13f95 100644
--- a/Trajectories/Tests/tests.json
+++ b/Trajectories/Tests/tests.json
@@ -109,8 +109,7 @@
 	[
 	    "$src_dir/Trajectories/draw_segments.py",
 	    "$PWD/Eurec4A_graph_anti/segments_cost_functions.gt",
-	    "segments.gv"
-	],
-	"symlink": ["$PWD/Eurec4A_graph_anti/traj_segm.json"]
+	    "segments.gv", "-t", "$PWD/Eurec4A_graph_anti/traj_segm.json"
+	]
     }
 ]
diff --git a/Trajectories/draw_segments.py b/Trajectories/draw_segments.py
index abd2f0e93bddee067647e7d8f8be623126b9995e..2555423c6e82d5187433b4dd03aaffa03a2e08e2 100755
--- a/Trajectories/draw_segments.py
+++ b/Trajectories/draw_segments.py
@@ -16,6 +16,8 @@ import argparse
 parser = argparse.ArgumentParser()
 parser.add_argument("input_file", help = "Graph-tool file")
 parser.add_argument("output_file", help = "Graphviz file")
+parser.add_argument("-t",
+                    help = "trajectory segments, JSON, to color trajectories")
 args = parser.parse_args()
 
 g_in = graph_tool.load_graph(args.input_file)
@@ -33,12 +35,9 @@ for e in g_in.edges():
     except AttributeError:
         g_out.add_edge(g_in.vp.name[source], g_in.vp.name[target])
 
-try:
-    with open("traj_segm.json") as f: traj_segm = json.load(f)
-except FileNotFoundError:
-    print("traj_segm.json not found")
-    print("Will not color trajectories.")
-else:
+if args.t:
+    with open(args.t) as f: traj_segm = json.load(f)
+
     for segment_list in traj_segm:
         for i in range(len(segment_list) - 1):
             e = g_out.get_edge(segment_list[i], segment_list[i + 1])