diff --git a/api/s4_tanks.py b/api/s4_tanks.py
index 53388f0..5c5c88d 100644
--- a/api/s4_tanks.py
+++ b/api/s4_tanks.py
@@ -145,10 +145,13 @@ def delete_tank(name: str, cs: ChangeSet) -> ChangeSet:
 
 
 #--------------------------------------------------------------
-# [EPANET2][IN][OUT]
+# [EPANET2]
+# [IN]
 #   id elev initlevel minlevel maxlevel diam (minvol vcurve overflow) ;desc
 #                                                      xxx
 #                                                       *      YES
+# [OUT]
+#   id elev initlevel minlevel maxlevel diam minvol (vcurve overflow) ;desc
 #--------------------------------------------------------------
 class InpTank:
     def __init__(self, line: str) -> None:
@@ -164,7 +167,7 @@ class InpTank:
         self.min_level = float(tokens[3])
         self.max_level = float(tokens[4])
         self.diameter = float(tokens[5])
-        self.min_vol = float(tokens[6])
+        self.min_vol = float(tokens[6]) if num_without_desc >= 7 else 0.0
         self.vol_curve = str(tokens[7]) if num_without_desc >= 8 and tokens[7] != '*' else None
         self.overflow = str(tokens[8].upper()) if num_without_desc >= 9 else None
         self.desc = str(tokens[-1]) if has_desc else None