diff --git a/Airlock/Airlock.cs b/Airlock/Airlock.cs
index cc3ac27..ca64240 100644
--- a/Airlock/Airlock.cs
+++ b/Airlock/Airlock.cs
@@ -61,6 +61,8 @@ namespace IngameScript
 
             public bool Cycling { get; private set; } = false;
 
+            public IMyAirVent ReferenceVent { get; set; }
+
             private bool DoorOpened
             {
                 get
@@ -69,19 +71,6 @@ namespace IngameScript
                 }
             }
 
-            // Returns false if we are in a state where we can't or don't need to balance
-            private bool balanceOxygen()
-            {
-                if (_innerDoor.Status == DoorStatus.Closed || _outerDoor.Status == DoorStatus.Open || OxygenBalanced) { return false; }
-
-                _console.Print($"{_name}: Balancing Oxygen Tank");
-
-                // Configure the vent to suck in Oxygen.
-                _airVent.Depressurize = true;
-                _airVent.Enabled = true;
-                return true;
-            }
-
             private string _name;
             private PrefixedConsole _console;
             private MyIni _ini;
@@ -92,7 +81,6 @@ namespace IngameScript
             private List<IMyLightingBlock> _lights;
             private IMyGasTank _oxygenTank;
             private IMyAirVent _airVent;
-            private IMyAirVent _airSensor;
             // private List<IMyTextSurface> _displays;
 
             private const int CooldownTicks = 120;
@@ -136,16 +124,10 @@ namespace IngameScript
             // Precondition: _ini.TryParse() should be called on the block before calling this function.
             private void addVent(IMyAirVent vent)
             {
-                if (_ini.Get("airlock", "ventRole").ToString() == "cycling" && _airVent == null)
-                {
+                if (_airVent == null) {
                     _airVent = vent;
                     return;
                 }
-                if (_ini.Get("airlock", "ventRole").ToString() == "reference" && _airSensor == null)
-                {
-                    _airSensor = vent;
-                    return;
-                }
                 _console.Print($"Couldn't add air vent '{vent.CustomName}'");
             }
 
@@ -232,9 +214,9 @@ namespace IngameScript
 
                 // When depressurizing, check the external pressure and only depressurize to that value.
                 // TODO: test this for floating point errors
-                if (_airVent.Depressurize && _airSensor != null)
+                if (_airVent.Depressurize && ReferenceVent != null)
                 {
-                    targetOxygenLevel = _airSensor.GetOxygenLevel();
+                    targetOxygenLevel = ReferenceVent.GetOxygenLevel();
                     _console.Print($"Set depressurization target to {targetOxygenLevel}");
                 }
             }
@@ -295,6 +277,19 @@ namespace IngameScript
             //     }
             // }
 
+            // Returns false if we are in a state where we can't or don't need to balance
+            private bool balanceOxygen()
+            {
+                if (_innerDoor.Status == DoorStatus.Closed || _outerDoor.Status == DoorStatus.Open || OxygenBalanced) { return false; }
+
+                _console.Print($"{_name}: Balancing Oxygen Tank");
+
+                // Configure the vent to suck in Oxygen.
+                _airVent.Depressurize = true;
+                _airVent.Enabled = true;
+                return true;
+            }
+
             private void lockDoors()
             {
                 _innerDoor.Enabled = false;
diff --git a/Airlock/Program.cs b/Airlock/Program.cs
index 2e34dc1..807cab0 100644
--- a/Airlock/Program.cs
+++ b/Airlock/Program.cs
@@ -1,4 +1,5 @@
 using Sandbox.ModAPI.Ingame;
+using SpaceEngineers.Game.ModAPI.Ingame;
 using System.Collections.Generic;
 using VRage.Game.ModAPI.Ingame.Utilities;
 
@@ -23,10 +24,25 @@ namespace IngameScript
             _airlocks = new Dictionary<string, Airlock>();
 
             List<IMyTerminalBlock> airlockBlocks = new List<IMyTerminalBlock>();
-            GridTerminalSystem.GetBlocksOfType(airlockBlocks, block => _ini.ContainsSection("airlock"));
+            GridTerminalSystem.GetBlocksOfType(airlockBlocks, block => MyIni.HasSection(block.CustomData, "airlock"));
+            IMyAirVent referenceVent = null;
             foreach (IMyTerminalBlock block in airlockBlocks)
             {
                 _ini.TryParse(block.CustomData, "airlock");
+
+                // TODO: redundant reference vents would be awesome. Everyone loves redundancy
+                if (block is IMyAirVent && _ini.Get("airlock", "reference").ToBoolean())
+                {
+                    if (referenceVent != null) {
+                        _console.Print("Found multiple reference vents. Only the first one will be used.");
+                        continue;
+                    }
+
+                    referenceVent = block as IMyAirVent;
+                    _console.Print($"Found reference vent {block.CustomName}.");
+                    continue;
+                }
+
                 string airlockName = _ini.Get("airlock", "id").ToString();
                 if (!_airlocks.ContainsKey(airlockName))
                 {
@@ -34,11 +50,10 @@ namespace IngameScript
                 }
 
                 _airlocks[airlockName].AddBlock(block);
-
-
-                // TODO: it would be most convenient to just delete non-functional Airlocks... but maybe they're worth
-                // keeping around for warnings.
             }
+
+            if (referenceVent != null) foreach (Airlock airlock in _airlocks.Values) { airlock.ReferenceVent = referenceVent; }
+
             _console.Print($"Found {_airlocks.Count} airlocks.");
             _console.PrintLower($"Airlock Controller\nTotal Ticks: 0");
         }