diff --git a/src/composer.ts b/src/composer.ts
index 319cbed9..5cf1f0ca 100644
--- a/src/composer.ts
+++ b/src/composer.ts
@@ -108,7 +108,7 @@ function generateBotErrorMessage(error: unknown) {
                 msg += `: ${error}`;
                 break;
             case "string":
-                msg += `: ${String(error).substr(0, 50)}`;
+                msg += `: ${String(error).substring(0, 50)}`;
                 break;
             default:
                 msg += "!";
@@ -384,24 +384,22 @@ export class Composer<C extends Context> implements MiddlewareObj<C> {
             if (cmd.startsWith("/")) {
                 throw new Error(
                     `Do not include '/' when registering command handlers (use '${
-                        cmd.substr(1)
+                        cmd.substring(1)
                     }' not '${cmd}')`,
                 );
             }
             const set = cmd.indexOf("@") === -1 ? noAtCommands : atCommands;
             set.add(cmd);
         });
-        return this.on(":entities:bot_command").filter(
+        return this.on("message:entities:bot_command").filter(
             (ctx): ctx is CommandContext<C> => {
-                const msg = ctx.message ?? ctx.channelPost;
-                const txt = msg.text ?? msg.caption;
-                const entities = msg.entities ?? msg.caption_entities;
-                return entities.some((e) => {
+                const txt = ctx.message.text;
+                return ctx.message.entities.some((e) => {
                     if (e.type !== "bot_command") return false;
                     if (e.offset !== 0) return false;
                     const cmd = txt.substring(1, e.length);
                     if (noAtCommands.has(cmd) || atCommands.has(cmd)) {
-                        ctx.match = txt.substr(cmd.length + 1).trimStart();
+                        ctx.match = txt.substring(cmd.length + 1).trimStart();
                         return true;
                     }
                     const index = cmd.indexOf("@");
@@ -410,7 +408,7 @@ export class Composer<C extends Context> implements MiddlewareObj<C> {
                     if (atTarget !== ctx.me.username) return false;
                     const atCommand = cmd.substring(0, index);
                     if (noAtCommands.has(atCommand)) {
-                        ctx.match = txt.substr(cmd.length + 1).trimStart();
+                        ctx.match = txt.substring(cmd.length + 1).trimStart();
                         return true;
                     }
                     return false;
@@ -833,7 +831,7 @@ type HearsContext<C extends Context> = Filter<
 >;
 type CommandContext<C extends Context> = Filter<
     C & { match: string },
-    ":entities:bot_command"
+    "message:entities:bot_command"
 >;
 
 function match<C extends Context>(
diff --git a/src/core/client.ts b/src/core/client.ts
index 7a55a192..30ad2c48 100644
--- a/src/core/client.ts
+++ b/src/core/client.ts
@@ -216,7 +216,7 @@ class ApiClient<R extends RawApi> {
         if (this.options.apiRoot.endsWith("/")) {
             throw new Error(
                 `Remove the trailing '/' from the 'apiRoot' option (use '${
-                    this.options.apiRoot.substr(
+                    this.options.apiRoot.substring(
                         0,
                         this.options.apiRoot.length - 1,
                     )