--- a/devtools/shim/devtools-startup.js
+++ b/devtools/shim/devtools-startup.js
@@ -527,17 +527,19 @@ DevToolsStartup.prototype = {
         return;
       }
     }
 
     let url = "about:devtools";
     if (reason) {
       url += "?reason=" + encodeURIComponent(reason);
     }
-    gBrowser.selectedTab = gBrowser.addTab(url);
+
+    // Set relatedToCurrent: true to open the tab next to the current one.
+    gBrowser.selectedTab = gBrowser.addTab(url, {relatedToCurrent: true});
   },
 
   handleConsoleFlag: function (cmdLine) {
     let window = Services.wm.getMostRecentWindow("devtools:webconsole");
     if (!window) {
       let require = this.initDevTools("CommandLine");
       let { HUDService } = require("devtools/client/webconsole/hudservice");
       let { console } = Cu.import("resource://gre/modules/Console.jsm", {});