diff --git a/README.md b/README.md
index 9895b36e3..e94183f15 100644
--- a/README.md
+++ b/README.md
@@ -28,7 +28,7 @@
## 🖥️ Compatibility
-Zen is currently built using Firefox version `137.0.2`! 🚀
+Zen is currently built using Firefox version `138.0b9`! 🚀
- [`Zen Twilight`](https://zen-browser.app/download?twilight) - Is currently built using Firefox version `RC 137.0.2`!
- Check out the latest [release notes](https://zen-browser.app/release-notes)!
diff --git a/src/Cargo-toml.patch b/src/Cargo-toml.patch
index c101b8190..841496923 100644
--- a/src/Cargo-toml.patch
+++ b/src/Cargo-toml.patch
@@ -1,14 +1,14 @@
diff --git a/Cargo.toml b/Cargo.toml
-index a99b447250d36dd0146e031fa22503bc88eeae39..86829fc7075054f832a04825c98325a925cf5b0f 100644
+index d3d529b487f80d4b4f3bfa13cdd3f62946352db8..b35a9e0e3339d48d1cd0cab7b22d030f330e40d1 100644
--- a/Cargo.toml
+++ b/Cargo.toml
-@@ -205,6 +205,9 @@ rure = { path = "third_party/rust/rure" }
+@@ -217,6 +217,9 @@ rure = { path = "third_party/rust/rure" }
# Patch `plist` to work with `indexmap` 2.*
plist = { path = "third_party/rust/plist" }
+# Patch mime_guess to add missing mime types
+mime_guess = { path = "third_party/rust/mime_guess" }
+
- # To-be-published changes.
- unicode-bidi = { git = "https://github.com/servo/unicode-bidi", rev = "ca612daf1c08c53abe07327cb3e6ef6e0a760f0c" }
- nss-gk-api = { git = "https://github.com/beurdouche/nss-gk-api", rev = "e48a946811ffd64abc78de3ee284957d8d1c0d63" }
+ # Patch `unicode-width` 0.1.* to 0.2.
+ unicode-width = { path = "build/rust/unicode-width" }
+
diff --git a/src/browser/base/content/browser-box-inc-xhtml.patch b/src/browser/base/content/browser-box-inc-xhtml.patch
index 42dc4390d..9fc91dc5d 100644
--- a/src/browser/base/content/browser-box-inc-xhtml.patch
+++ b/src/browser/base/content/browser-box-inc-xhtml.patch
@@ -1,14 +1,14 @@
diff --git a/browser/base/content/browser-box.inc.xhtml b/browser/base/content/browser-box.inc.xhtml
-index 2ca8bdd2674fb4addf3bbf94ff17abc5c93c6293..dd965d8d190e8cdacbeb3d80995ad1a906e64079 100644
+index 7d7e8697f02f90d4f336c9ab0a73a89848e0c21c..d113b439888d26629ce5f6b5d35f8fa12249774b 100644
--- a/browser/base/content/browser-box.inc.xhtml
+++ b/browser/base/content/browser-box.inc.xhtml
-@@ -26,7 +26,13 @@
-
-
-
+@@ -23,7 +23,13 @@
+
+
+
+
-+
-+
++
++
+#include zen-tabbrowser-elements.inc.xhtml
diff --git a/src/browser/base/content/browser-xhtml.patch b/src/browser/base/content/browser-xhtml.patch
index 527fb79dc..2778cc0c8 100644
--- a/src/browser/base/content/browser-xhtml.patch
+++ b/src/browser/base/content/browser-xhtml.patch
@@ -1,5 +1,5 @@
diff --git a/browser/base/content/browser.xhtml b/browser/base/content/browser.xhtml
-index 0d0a559a6473149b50f4bf18d059e86907c4acd3..25ad798eb26f04262d069fdaf1f3fb00adec9807 100644
+index 51a25aaa5558e6e17246d54a7ed95d5ddf3ecdab..b49984c8711fc9f5f19f0cf6ecca07a8cca0d125 100644
--- a/browser/base/content/browser.xhtml
+++ b/browser/base/content/browser.xhtml
@@ -26,6 +26,7 @@
@@ -10,35 +10,28 @@ index 0d0a559a6473149b50f4bf18d059e86907c4acd3..25ad798eb26f04262d069fdaf1f3fb00
persist="screenX screenY width height sizemode"
data-l10n-sync="true">
-@@ -104,6 +105,8 @@
+@@ -104,8 +105,11 @@
+#include zen-preloaded.inc.xhtml
+
- # All JS files which are needed by browser.xhtml and other top level windows to
- # support MacOS specific features *must* go into the global-scripts.inc file so
- # that they can be shared with macWindow.inc.xhtml.
-@@ -148,6 +151,7 @@
- window.addEventListener("DOMContentLoaded",
- gBrowserInit.onDOMContentLoaded.bind(gBrowserInit), { once: true });
-
+
+
+#include zen-assets.inc.xhtml
# All sets except for popupsets (commands, keys, and stringbundles)
-@@ -169,9 +173,11 @@
+@@ -127,9 +131,12 @@
--#include navigator-toolbox.inc.xhtml
--
--#include browser-box.inc.xhtml
-+
-+
-+ #include navigator-toolbox.inc.xhtml
-+ #include browser-box.inc.xhtml
-+
++
++
+ #include navigator-toolbox.inc.xhtml
+
+ #include browser-box.inc.xhtml
++
-@@ -17,9 +17,8 @@
+@@ -17,9 +17,9 @@
#include browser-menubar.inc
-#include titlebar-items.inc.xhtml
--
+
+
-
--
-+
-
-
-
-
@@ -50,6 +50,10 @@
tooltip="tabbrowser-tab-tooltip"
orient="horizontal"
- stopwatchid="FX_TAB_CLICK_MS">
+ stopwatchid="tabClick">
+
+
+
+
+
# If the name (tabbrowser-arrowscrollbox) or structure of this changes
- # significantly, there is an optimization in
-@@ -75,6 +79,8 @@
+@@ -76,6 +80,8 @@
tooltip="dynamic-shortcut-tooltip"
data-l10n-id="tabs-toolbar-new-tab"/>
@@ -59,7 +42,7 @@ index feb9e4ef7e872b4cfbf0d55f24a34db275951c66..3ce9b9919ff736885b8aa8943bbbce3c
@@ -67,20 +50,7 @@ index feb9e4ef7e872b4cfbf0d55f24a34db275951c66..3ce9b9919ff736885b8aa8943bbbce3c
+#include zen-sidebar-icons.inc.xhtml
--
+
+
-
-+#include titlebar-items.inc.xhtml
-
- #include private-browsing-indicator.inc.xhtml
-
--#include titlebar-items.inc.xhtml
-
-
-