diff --git a/ext/src/background/ShimManager.ts b/ext/src/background/ShimManager.ts
index 8fbd69c..b718be5 100644
--- a/ext/src/background/ShimManager.ts
+++ b/ext/src/background/ShimManager.ts
@@ -158,7 +158,7 @@ export default new class ShimManager {
                 break;
             }
 
-            case "main:/selectReceiverBegin": {
+            case "main:selectReceiver": {
                 if (shim.contentTabId === undefined
                  || shim.contentFrameId === undefined) {
                     throw logger.error("Shim associated with content sender missing tab/frame ID");
@@ -174,7 +174,7 @@ export default new class ShimManager {
                     // Handle cancellation
                     if (!selection) {
                         shim.contentPort.postMessage({
-                            subject: "shim:/selectReceiverCancelled"
+                            subject: "shim:selectReceiver/cancelled"
                         });
 
                         break;
@@ -191,7 +191,7 @@ export default new class ShimManager {
                                     ReceiverSelectorMediaType.App) {
 
                                 shim.contentPort.postMessage({
-                                    subject: "shim:/selectReceiverCancelled"
+                                    subject: "shim:selectReceiver/cancelled"
                                 });
 
                                 loadSender({
@@ -204,7 +204,7 @@ export default new class ShimManager {
                             }
 
                             shim.contentPort.postMessage({
-                                subject: "shim:/selectReceiverEnd"
+                                subject: "shim:selectReceiver/selected"
                               , data: selection
                             });
 
@@ -213,7 +213,7 @@ export default new class ShimManager {
 
                         case ReceiverSelectionActionType.Stop: {
                             shim.contentPort.postMessage({
-                                subject: "shim:/selectReceiverStop"
+                                subject: "shim:selectReceiver/stopped"
                               , data: selection
                             });
 
@@ -223,7 +223,7 @@ export default new class ShimManager {
                 } catch (err) {
                     // TODO: Report errors properly
                     shim.contentPort.postMessage({
-                        subject: "shim:/selectReceiverCancelled"
+                        subject: "shim:selectReceiver/cancelled"
                     });
                 }
 
diff --git a/ext/src/messaging.ts b/ext/src/messaging.ts
index bdf44ed..ba96d27 100644
--- a/ext/src/messaging.ts
+++ b/ext/src/messaging.ts
@@ -27,10 +27,10 @@ type MessagesBase = {
 
   , "main:/shimReady": { appId: string }
 
-  , "main:/selectReceiverBegin": {}
-  , "shim:/selectReceiverEnd": ReceiverSelectionCast
-  , "shim:/selectReceiverStop": ReceiverSelectionStop
-  , "shim:/selectReceiverCancelled": {}
+  , "main:selectReceiver": {}
+  , "shim:selectReceiver/selected": ReceiverSelectionCast
+  , "shim:selectReceiver/stopped": ReceiverSelectionStop
+  , "shim:selectReceiver/cancelled": {}
 
   , "main:/sessionCreated": {}
 
diff --git a/ext/src/shim/cast/index.ts b/ext/src/shim/cast/index.ts
index de1aabb..2a84953 100755
--- a/ext/src/shim/cast/index.ts
+++ b/ext/src/shim/cast/index.ts
@@ -172,7 +172,7 @@ export function requestSession (
 
     // Open destination chooser
     sendMessageResponse({
-        subject: "main:/selectReceiverBegin"
+        subject: "main:selectReceiver"
     });
 }
 
@@ -323,7 +323,7 @@ onMessage(async message => {
             break;
         }
 
-        case "shim:/selectReceiverEnd": {
+        case "shim:selectReceiver/selected": {
             logger.info("Selected receiver");
 
             if (!sessionRequestInProgress) {
@@ -377,7 +377,7 @@ onMessage(async message => {
             break;
         }
 
-        case "shim:/selectReceiverStop": {
+        case "shim:selectReceiver/stopped": {
             logger.info("Stopped receiver");
 
             if (sessionRequestInProgress) {
@@ -400,7 +400,7 @@ onMessage(async message => {
         /**
          * Popup closed before session established.
          */
-        case "shim:/selectReceiverCancelled": {
+        case "shim:selectReceiver/cancelled": {
             if (sessionRequestInProgress) {
                 sessionRequestInProgress = false;