diff --git a/boostmovehub.ts b/boostmovehub.ts
index 8b8525f..f08191b 100644
--- a/boostmovehub.ts
+++ b/boostmovehub.ts
@@ -76,7 +76,7 @@ export class BoostMoveHub extends LPF2Hub {
      */
     public setMotorSpeed (port: string, speed: number, time?: number) {
         return new Promise((resolve, reject) => {
-            const portObj = this._ports[port];
+            const portObj = this._portLookup(port);
             if (time) {
                 if (portObj.type === Consts.Devices.BOOST_INTERACTIVE_MOTOR || portObj.type === Consts.Devices.BOOST_MOVE_HUB_MOTOR) {
                     portObj.busy = true;
@@ -113,7 +113,7 @@ export class BoostMoveHub extends LPF2Hub {
      * @returns {Promise} Resolved upon successful completion of command (ie. once the motor is finished).
      */
     public setMotorAngle (port: string, angle: number, speed: number = 100) {
-        const portObj = this._ports[port];
+        const portObj = this._portLookup(port);
         if (!(portObj.type === Consts.Devices.BOOST_INTERACTIVE_MOTOR || portObj.type === Consts.Devices.BOOST_MOVE_HUB_MOTOR)) {
             throw new Error("Angle rotation is only available when using a Boost Interactive Motor or Boost Move Hub Motor");
         }
diff --git a/hub.ts b/hub.ts
index 8188ee4..fcd37c8 100644
--- a/hub.ts
+++ b/hub.ts
@@ -169,11 +169,11 @@ export class Hub extends EventEmitter {
      */
     public subscribe (port: string, mode?: number) {
         return new Promise((resolve, reject) => {
-            let newMode = this._getModeForDeviceType(this._ports[port].type);
+            let newMode = this._getModeForDeviceType(this._portLookup(port).type);
             if (mode) {
                 newMode = mode;
             }
-            this._activatePortDevice(this._ports[port].value, this._ports[port].type, newMode, 0x00, () => {
+            this._activatePortDevice(this._portLookup(port).value, this._portLookup(port).type, newMode, 0x00, () => {
                 return resolve();
             });
         });
@@ -187,8 +187,8 @@ export class Hub extends EventEmitter {
      */
     public unsubscribe (port: string) {
         return new Promise((resolve, reject) => {
-            const mode = this._getModeForDeviceType(this._ports[port].type);
-            this._deactivatePortDevice(this._ports[port].value, this._ports[port].type, mode, 0x00, () => {
+            const mode = this._getModeForDeviceType(this._portLookup(port).type);
+            this._deactivatePortDevice(this._portLookup(port).value, this._portLookup(port).type, mode, 0x00, () => {
                 return resolve();
             });
         });
@@ -310,6 +310,14 @@ export class Hub extends EventEmitter {
     }
 
 
+    protected _portLookup (port: string) {
+        if (!this._ports[port]) {
+            throw new Error(`Port ${port} does not exist on this Hub type`);
+        }
+        return this._ports[port];
+    }
+
+
     private _getModeForDeviceType (type: Consts.Devices) {
         switch (type) {
             case Consts.Devices.BASIC_MOTOR:
diff --git a/puphub.ts b/puphub.ts
index 5c43dca..e17b666 100644
--- a/puphub.ts
+++ b/puphub.ts
@@ -80,7 +80,7 @@ export class PUPHub extends LPF2Hub {
      */
     public setMotorSpeed (port: string, speed: number, time?: number) {
         return new Promise((resolve, reject) => {
-            const portObj = this._ports[port];
+            const portObj = this._portLookup(port);
             if (time) {
                 const data = Buffer.from([0x0a, 0x00, 0x81, portObj.value, 0x11, 0x60, 0x00, this._mapSpeed(speed), 0x00, 0x00]);
                 this._writeMessage(Consts.BLECharacteristics.LPF2_ALL, data);
diff --git a/wedo2hub.ts b/wedo2hub.ts
index 7cb937e..250662e 100644
--- a/wedo2hub.ts
+++ b/wedo2hub.ts
@@ -102,10 +102,10 @@ export class WeDo2Hub extends Hub {
      */
     public setMotorSpeed (port: string, speed: number, time?: number) {
         return new Promise((resolve, reject) => {
-            this._writeMessage(Consts.BLECharacteristics.WEDO2_MOTOR_VALUE_WRITE, Buffer.from([this._ports[port].value, 0x01, 0x02, this._mapSpeed(speed)]));
+            this._writeMessage(Consts.BLECharacteristics.WEDO2_MOTOR_VALUE_WRITE, Buffer.from([this._portLookup(port).value, 0x01, 0x02, this._mapSpeed(speed)]));
             if (time) {
                 setTimeout(() => {
-                    this._writeMessage(Consts.BLECharacteristics.WEDO2_MOTOR_VALUE_WRITE, Buffer.from([this._ports[port].value, 0x01, 0x02, 0x00]));
+                    this._writeMessage(Consts.BLECharacteristics.WEDO2_MOTOR_VALUE_WRITE, Buffer.from([this._portLookup(port).value, 0x01, 0x02, 0x00]));
                     return resolve();
                 }, time);
             } else {