diff --git a/src/commands/dev/index.js b/src/commands/dev/index.js
index 3ebc80d..8578c77 100644
--- a/src/commands/dev/index.js
+++ b/src/commands/dev/index.js
@@ -212,11 +212,19 @@ class DevCommand extends Command {
       settings = {
         noCmd: true,
         port: 8888,
-        proxyPort: 3999,
+        proxyPort: await getPort({ port: 3999 }),
         dist
       };
     }
 
+    // Reset port if not manually specified, to make it dynamic
+    if (!(config.dev && config.dev.port) && !flags.port) {
+      settings = {
+        port: await getPort({ port: settings.port }),
+        ...settings
+      };
+    }
+
     startDevServer(settings, this.log);
 
     // serve functions from zip-it-and-ship-it