diff --git a/pkgs/applications/networking/browsers/firefox/common.nix b/pkgs/applications/networking/browsers/firefox/common.nix
index 933740bef768..883c04a5a676 100644
--- a/pkgs/applications/networking/browsers/firefox/common.nix
+++ b/pkgs/applications/networking/browsers/firefox/common.nix
@@ -54,6 +54,7 @@
 , glib
 , gnum4
 , gtk3
+, icu
 , icu72
 , libGL
 , libGLU
@@ -440,9 +441,6 @@ buildStdenv.mkDerivation ({
     freetype
     glib
     gtk3
-    # icu73 changed how it follows symlinks which breaks in the firefox sandbox
-    # https://bugzilla.mozilla.org/show_bug.cgi?id=1839287
-    icu72
     libffi
     libGL
     libGLU
@@ -470,6 +468,9 @@ buildStdenv.mkDerivation ({
     zip
     zlib
   ]
+  # icu73 changed how it follows symlinks which breaks in the firefox sandbox
+  # https://bugzilla.mozilla.org/show_bug.cgi?id=1839287
+  ++ [ (if (lib.versionAtLeast version "115") then icu else icu72) ]
   ++ [ (if (lib.versionAtLeast version "103") then nss_latest else nss_esr) ]
   ++ lib.optional  alsaSupport alsa-lib
   ++ lib.optional  jackSupport libjack2
diff --git a/pkgs/applications/networking/browsers/firefox/packages.nix b/pkgs/applications/networking/browsers/firefox/packages.nix
index f781997587a4..5ef29b15e7be 100644
--- a/pkgs/applications/networking/browsers/firefox/packages.nix
+++ b/pkgs/applications/networking/browsers/firefox/packages.nix
@@ -29,11 +29,11 @@
 
   firefox-beta = buildMozillaMach rec {
     pname = "firefox-beta";
-    version = "114.0b7";
+    version = "115.0b7";
     applicationName = "Mozilla Firefox Beta";
     src = fetchurl {
       url = "mirror://mozilla/firefox/releases/${version}/source/firefox-${version}.source.tar.xz";
-      sha512 = "6cfcaa08d74d6e123047cd33c1bc2e012e948890ea8bab5feb43459048a41c10f6bc549241386a3c81d438b59e966e7949161fe3f18b359ec8659bdf2ba0f187";
+      sha512 = "4ae6b74e7a47c06c3630c911d5bbcd6c390f1462f4335c8fd084cf455675c88872864390e22847da16564484b70fbac09625015fc6a4cf10a01ed8052016991e";
     };
 
     meta = {
@@ -56,12 +56,12 @@
 
   firefox-devedition = buildMozillaMach rec {
     pname = "firefox-devedition";
-    version = "114.0b7";
+    version = "115.0b7";
     applicationName = "Mozilla Firefox Developer Edition";
     branding = "browser/branding/aurora";
     src = fetchurl {
       url = "mirror://mozilla/devedition/releases/${version}/source/firefox-${version}.source.tar.xz";
-      sha512 = "2aa9ec2eb57b6debe3a15ac43f4410a4d649c8373725be8ed2540effa758d970e29c9ca675d9ac27a4b58935fc428aaf8b84ecd769b88f3607e911178492ebf1";
+      sha512 = "f360ca7c5eb69d16a54b37a95195f4981c19e7e081cf7d494dafc1838ec69f2beabae5eaed23b0b551e71b32e3d0213383bc43e63416d390aa453bfa8b0f1993";
     };
 
     meta = {