diff --git a/flatland/envs/rail_generators.py b/flatland/envs/rail_generators.py
index 1b72b9788dcf67028fbf5deea7a3f2a7e1cfa1e6..c100e3db88dcc8f2a42396baf8e6565cb14dcc48 100644
--- a/flatland/envs/rail_generators.py
+++ b/flatland/envs/rail_generators.py
@@ -714,7 +714,8 @@ def sparse_rail_generator(num_cities=5, num_intersections=4, num_trainstations=2
                                                 (station_x, station_y))
                 # Check if connection was made
                 if len(connection) == 0:
-                    train_stations[trainstation_node].pop(-1)
+                    if len(train_stations) > 0:
+                        train_stations[trainstation_node].pop(-1)
                 else:
                     built_num_trainstation += 1