diff --git a/proton b/proton
index 6d2ae03b..bd1c9c08 100755
--- a/proton
+++ b/proton
@@ -1436,6 +1436,8 @@ class Session:
                         self.log_file.write("System " + var + ": " + os.environ[var] + "\n")
                     if var in used_user_settings:
                         self.log_file.write("User settings " + var + ": " + used_user_settings[var] + "\n")
+                    if var in self.env:
+                        self.log_file.write("Effective " + var + ": " + self.env[var] + "\n")
 
                 self.log_file.write("======================\n")
                 self.log_file.flush()