diff --git a/flatland/envs/rail_env.py b/flatland/envs/rail_env.py
index e86618baba4fa487d13dcadd9ca261a107936efd..ae3169f298ddd686d834d4a8bd571f4403dbbb79 100644
--- a/flatland/envs/rail_env.py
+++ b/flatland/envs/rail_env.py
@@ -738,7 +738,7 @@ class RailEnv(Environment):
                 print("[WARNING] Unable to save the distance map for this environment, as none was found !")
 
         else:
-            with open(filename, "wb") as file_out:
+            with open(filename,"wb") as file_out:
                 file_out.write(self.get_full_state_msg())
 
     def load(self, filename):