--- a/browser/components/extensions/ext-commands.js
+++ b/browser/components/extensions/ext-commands.js
@@ -162,21 +162,22 @@ this.commands = class extends ExtensionA
     let parts = shortcut.split("+");
 
     // The key is always the last element.
     let chromeKey = parts.pop();
 
     // The modifiers are the remaining elements.
     keyElement.setAttribute("modifiers", this.getModifiersAttribute(parts));
 
-    if (/^[A-Z0-9]$/.test(chromeKey)) {
+    if (/^[A-Z]$/.test(chromeKey)) {
       // We use the key attribute for all single digits and characters.
       keyElement.setAttribute("key", chromeKey);
     } else {
       keyElement.setAttribute("keycode", this.getKeycodeAttribute(chromeKey));
+      keyElement.setAttribute("event", "keydown");
     }
 
     return keyElement;
   }
 
   /**
    * Determines the corresponding XUL keycode from the given chrome key.
    *
@@ -186,16 +187,19 @@ this.commands = class extends ExtensionA
    *    ---------------------------------------
    *    "PageUP"  |  "VK_PAGE_UP"
    *    "Delete"  |  "VK_DELETE"
    *
    * @param {string} chromeKey The chrome key (e.g. "PageUp", "Space", ...)
    * @returns {string} The constructed value for the Key's 'keycode' attribute.
    */
   getKeycodeAttribute(chromeKey) {
+    if (/[0-9]/.test(chromeKey)) {
+      return `VK_${chromeKey}`;
+    }
     return `VK${chromeKey.replace(/([A-Z])/g, "_$&").toUpperCase()}`;
   }
 
   /**
    * Determines the corresponding XUL modifiers from the chrome modifiers.
    *
    * For example:
    *

--- a/browser/components/extensions/test/browser/browser_ext_commands_onCommand.js
+++ b/browser/components/extensions/test/browser/browser_ext_commands_onCommand.js
@@ -65,16 +65,25 @@ add_task(function* test_user_defined_com
       name: "toggle-ctrl-shift-left",
       shortcut: "Ctrl+Shift+Left",
       key: "VK_LEFT",
       modifiers: {
         accelKey: true,
         shiftKey: true,
       },
     },
+    {
+      name: "toggle-ctrl-shift-1",
+      shortcut: "Ctrl+Shift+1",
+      key: "1",
+      modifiers: {
+        accelKey: true,
+        shiftKey: true,
+      },
+    },
     // Alt+Shift Shortcuts
     {
       name: "toggle-alt-shift-1",
       shortcut: "Alt+Shift+1",
       key: "1",
       modifiers: {
         altKey: true,
         shiftKey: true,
@@ -132,16 +141,41 @@ add_task(function* test_user_defined_com
       name: "spaces-in-shortcut-name",
       shortcut: "  Alt + Shift + 2  ",
       key: "2",
       modifiers: {
         altKey: true,
         shiftKey: true,
       },
     },
+    {
+      name: "toggle-ctrl-space",
+      shortcut: "Ctrl+Space",
+      key: "VK_SPACE",
+      modifiers: {
+        accelKey: true,
+      },
+    },
+    {
+      name: "toggle-ctrl-comma",
+      shortcut: "Ctrl+Comma",
+      key: "VK_COMMA",
+      modifiers: {
+        accelKey: true,
+      },
+    },
+    {
+      name: "toggle-ctrl-period",
+      shortcut: "Ctrl+Period",
+      key: "VK_PERIOD",
+      modifiers: {
+        accelKey: true,
+      },
+    },
+
   ];
 
   // Create a window before the extension is loaded.
   let win1 = yield BrowserTestUtils.openNewBrowserWindow();
   yield BrowserTestUtils.loadURI(win1.gBrowser.selectedBrowser, "about:robots");
   yield BrowserTestUtils.browserLoaded(win1.gBrowser.selectedBrowser);
 
   let commands = {};