diff --git a/mobile/android/app/geckoview-prefs.js b/mobile/android/app/geckoview-prefs.js
index 8cde2963d8cb..509084e0df6e 100644
--- a/mobile/android/app/geckoview-prefs.js
+++ b/mobile/android/app/geckoview-prefs.js
@@ -95,3 +95,6 @@ pref("extensions.formautofill.loglevel", "Warn");
 pref("pdfjs.handleOctetStream", true);
 pref("browser.download.open_pdf_attachments_inline", true);
 pref("pdfjs.annotationEditorMode", -1);
+#ifdef NIGHTLY_BUILD
+  pref("pdfjs.enableFloatingToolbar", true);
+#endif
diff --git a/toolkit/components/pdfjs/test/test_pdf_file_in_iframe.html b/toolkit/components/pdfjs/test/test_pdf_file_in_iframe.html
index 333a46076aa0..81410c535fc7 100644
--- a/toolkit/components/pdfjs/test/test_pdf_file_in_iframe.html
+++ b/toolkit/components/pdfjs/test/test_pdf_file_in_iframe.html
@@ -18,6 +18,7 @@
             await SpecialPowers.pushPrefEnv({
               "set": [
                 ["pdfjs.disabled", false],
+                ["pdfjs.enableFloatingToolbar", false],
               ],
             });