diff --git a/ext/fg/js/float.js b/ext/fg/js/float.js
index 3b752df5..9f58439f 100644
--- a/ext/fg/js/float.js
+++ b/ext/fg/js/float.js
@@ -29,6 +29,8 @@ class DisplayFloat extends Display {
         this._windowMessageHandlers = new Map([
             ['extensionUnloaded', {async: false, handler: this._onMessageExtensionUnloaded.bind(this)}]
         ]);
+        this._browser = null;
+        this._copyTextarea = null;
 
         this.registerActions([
             ['copyHostSelection', () => this._copySelection()]
@@ -43,6 +45,9 @@ class DisplayFloat extends Display {
     async prepare() {
         await super.prepare();
 
+        const {browser} = await api.getEnvironmentInfo();
+        this._browser = browser;
+
         this.registerDirectMessageHandlers([
             ['configure',       {async: true,  handler: this._onMessageConfigure.bind(this)}],
             ['setContentScale', {async: false, handler: this._onMessageSetContentScale.bind(this)}]
@@ -150,10 +155,47 @@ class DisplayFloat extends Display {
 
     _copySelection() {
         if (window.getSelection().toString()) { return false; }
-        this._invokeOwner('copySelection');
+        this._copyHostSelection();
         return true;
     }
 
+    async _copyHostSelection() {
+        switch (this._browser) {
+            case 'firefox':
+            case 'firefox-mobile':
+                {
+                    let text;
+                    try {
+                        text = await this._invokeOwner('getSelectionText');
+                    } catch (e) {
+                        break;
+                    }
+                    this._copyText(text);
+                }
+                break;
+            default:
+                this._invokeOwner('copySelection');
+                break;
+        }
+    }
+
+    _copyText(text) {
+        const parent = document.body;
+        if (parent === null) { return; }
+
+        let textarea = this._copyTextarea;
+        if (textarea === null) {
+            textarea = document.createElement('textarea');
+            this._copyTextarea = textarea;
+        }
+
+        textarea.value = text;
+        parent.appendChild(textarea);
+        textarea.select();
+        document.execCommand('copy');
+        parent.removeChild(textarea);
+    }
+
     _setContentScale(scale) {
         const body = document.body;
         if (body === null) { return; }
diff --git a/ext/fg/js/frontend.js b/ext/fg/js/frontend.js
index 82a56f1e..2ee9b4a1 100644
--- a/ext/fg/js/frontend.js
+++ b/ext/fg/js/frontend.js
@@ -115,6 +115,7 @@ class Frontend {
             ['getUrl',                  {async: false, handler: this._onApiGetUrl.bind(this)}],
             ['closePopup',              {async: false, handler: this._onApiClosePopup.bind(this)}],
             ['copySelection',           {async: false, handler: this._onApiCopySelection.bind(this)}],
+            ['getSelectionText',        {async: false, handler: this._onApiGetSelectionText.bind(this)}],
             ['getPopupInfo',            {async: false, handler: this._onApiGetPopupInfo.bind(this)}],
             ['getDocumentInformation',  {async: false, handler: this._onApiGetDocumentInformation.bind(this)}]
         ]);
@@ -168,9 +169,14 @@ class Frontend {
     }
 
     _onApiCopySelection() {
+        // This will not work on Firefox if a popup has focus, which is usually the case when this function is called.
         document.execCommand('copy');
     }
 
+    _onApiGetSelectionText() {
+        return document.getSelection().toString();
+    }
+
     _onApiGetPopupInfo() {
         return {
             popupId: (this._popup !== null ? this._popup.id : null)
diff --git a/ext/mixed/js/display.js b/ext/mixed/js/display.js
index c0102379..f79ba303 100644
--- a/ext/mixed/js/display.js
+++ b/ext/mixed/js/display.js
@@ -466,7 +466,7 @@ class Display extends EventDispatcher {
             this._closePopups();
             this._setEventListenersActive(false);
 
-            let asigned = false;
+            let assigned = false;
             const eventArgs = {type, urlSearchParams, token};
             this._historyHasChanged = true;
             this._contentType = type;
@@ -476,7 +476,7 @@ class Display extends EventDispatcher {
                 case 'kanji':
                     {
                         const isTerms = (type === 'terms');
-                        asigned = await this._setContentTermsOrKanji(token, isTerms, urlSearchParams, eventArgs);
+                        assigned = await this._setContentTermsOrKanji(token, isTerms, urlSearchParams, eventArgs);
                     }
                     break;
                 case 'unloaded':
@@ -485,14 +485,14 @@ class Display extends EventDispatcher {
                         eventArgs.content = content;
                         this.trigger('contentUpdating', eventArgs);
                         this._setContentExtensionUnloaded();
-                        asigned = true;
+                        assigned = true;
                     }
                     break;
             }
 
             const stale = (this._setContentToken !== token);
             if (!stale) {
-                if (!asigned) {
+                if (!assigned) {
                     type = 'clear';
                     this._contentType = type;
                     const {content} = this._history;
@@ -910,9 +910,7 @@ class Display extends EventDispatcher {
             container.appendChild(entry);
         }
 
-        if (typeof focusEntry === 'number') {
-            this._focusEntry(focusEntry, false);
-        }
+        this._focusEntry(typeof focusEntry === 'number' ? focusEntry : 0, false);
         if (typeof scrollX === 'number' || typeof scrollY === 'number') {
             let {x, y} = this._windowScroll;
             if (typeof scrollX === 'number') { x = scrollX; }