diff --git a/app/config.sh b/app/config.sh
index 487cd687d7..9725d34d8a 100644
--- a/app/config.sh
+++ b/app/config.sh
@@ -3,7 +3,7 @@ DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 # Version of Gecko to build with
 GECKO_VERSION_MAC="115.4.0esr"
 GECKO_VERSION_LINUX="115.5.0esr"
-GECKO_VERSION_WIN="102.13.0esr"
+GECKO_VERSION_WIN="115.5.0esr"
 RUST_VERSION=1.69.0
 
 # URL prefix for custom builds of Firefox components
diff --git a/app/win/mozconfig b/app/win/mozconfig
index 5f138b328f..a87dbccc83 100644
--- a/app/win/mozconfig
+++ b/app/win/mozconfig
@@ -1,29 +1,29 @@
-# Set Z_ARCH=win32 on command line to build and package win32
-if [ "$Z_ARCH" == "win32" ]; then
-	ac_add_options --target=i686-pc-mingw32
-	# https://bugzilla.mozilla.org/show_bug.cgi?id=1804548
-	ac_add_options --without-wasm-sandboxed-libraries
-fi
-
-ac_add_options --enable-bootstrap
-mk_add_options AUTOCLOBBER=1
-
-# These don't all affect the stub, but they can't hurt, and we'll want them if
-# we switch to custom XUL builds
-ac_add_options MOZ_ENABLE_JS_DUMP=1
-ac_add_options MOZ_ENABLE_FORKSERVER=
-ac_add_options MOZ_TELEMETRY_REPORTING=
-ac_add_options MOZ_DATA_REPORTING=
-ac_add_options --disable-tests
-ac_add_options --disable-debug
-ac_add_options --disable-debug-symbols
-ac_add_options --disable-webrtc
-ac_add_options --disable-eme
-ac_add_options --enable-official-branding
-
-export MOZILLA_OFFICIAL=1
-export RELEASE_OR_BETA=1
-MOZ_REQUIRE_SIGNING=
-
-# Build updater without MAR signature verification
-ac_add_options --disable-verify-mar
+# Set Z_ARCH=win32 on command line to build and package win32
+if [ "$Z_ARCH" == "win32" ]; then
+	ac_add_options --target=i686-pc-mingw32
+	# https://bugzilla.mozilla.org/show_bug.cgi?id=1804548
+	ac_add_options --without-wasm-sandboxed-libraries
+fi
+
+ac_add_options --enable-bootstrap
+mk_add_options AUTOCLOBBER=1
+
+# These don't all affect the stub, but they can't hurt, and we'll want them if
+# we switch to custom XUL builds
+ac_add_options MOZ_ENABLE_JS_DUMP=1
+ac_add_options MOZ_ENABLE_FORKSERVER=
+ac_add_options MOZ_TELEMETRY_REPORTING=
+ac_add_options MOZ_DATA_REPORTING=
+ac_add_options --disable-tests
+ac_add_options --disable-debug
+ac_add_options --disable-debug-symbols
+ac_add_options --disable-webrtc
+ac_add_options --disable-eme
+ac_add_options --enable-official-branding
+
+export MOZILLA_OFFICIAL=1
+export RELEASE_OR_BETA=1
+MOZ_REQUIRE_SIGNING=
+
+# Build updater without MAR signature verification
+ac_add_options --enable-unverified-updates
diff --git a/app/win/mozilla-115.patch b/app/win/mozilla-115.patch
new file mode 100644
index 0000000000..36ff1134cf
--- /dev/null
+++ b/app/win/mozilla-115.patch
@@ -0,0 +1,82 @@
+diff --git a/browser/app/nsBrowserApp.cpp b/browser/app/nsBrowserApp.cpp
+--- a/browser/app/nsBrowserApp.cpp
++++ b/browser/app/nsBrowserApp.cpp
+@@ -154,19 +154,30 @@ static bool IsArg(const char* arg, const
+ #endif
+ 
+   return false;
+ }
+ 
+ Bootstrap::UniquePtr gBootstrap;
+ 
+ static int do_main(int argc, char* argv[], char* envp[]) {
++  // Allow profile downgrade for Zotero
++  _putenv_s("MOZ_ALLOW_DOWNGRADE", "1");
++  // Don't create dedicated profile (default-esr)
++  _putenv_s("MOZ_LEGACY_PROFILES", "1");
++
+   // Allow firefox.exe to launch XULRunner apps via -app <application.ini>
+   // Note that -app must be the *first* argument.
+-  const char* appDataFile = getenv("XUL_APP_FILE");
++  UniqueFreePtr<char> iniPath = BinaryPath::GetApplicationIni();
++  if (!iniPath) {
++	  Output("Couldn't find application.ini.\n");
++	  return 255;
++
++  }
++  char *appDataFile = iniPath.get();
+   if ((!appDataFile || !*appDataFile) && (argc > 1 && IsArg(argv[1], "app"))) {
+     if (argc == 2) {
+       Output("Incorrect number of arguments passed to -app");
+       return 255;
+     }
+     appDataFile = argv[2];
+ 
+     char appEnv[MAXPATHLEN];
+diff --git a/xpcom/build/BinaryPath.h b/xpcom/build/BinaryPath.h
+--- a/xpcom/build/BinaryPath.h
++++ b/xpcom/build/BinaryPath.h
+@@ -283,16 +283,43 @@ class BinaryPath {
+     if (NS_FAILED(Get(path))) {
+       return nullptr;
+     }
+     UniqueFreePtr<char> result;
+     result.reset(strdup(path));
+     return result;
+   }
+ 
++  static UniqueFreePtr<char> GetApplicationIni() {
++	char path[MAXPATHLEN];
++	if (NS_FAILED(Get(path))) {
++		return nullptr;
++	}
++
++	char *c = path + strlen(path);
++	while (c >= path && *c != '\\' && *c != '/') {
++		*c = NULL;
++		c--;
++	}
++
++	if (c < path) {
++		return nullptr;
++	}
++
++	char iniPath[MAXPATHLEN];
++	int n = snprintf(iniPath, MAXPATHLEN, "%s\\app\\application.ini", path);
++	if (n < 0 || n >= MAXPATHLEN) {
++		return nullptr;
++	}
++
++	UniqueFreePtr<char> result;
++	result.reset(strdup(iniPath));
++	return result;
++  }
++
+ #ifdef MOZILLA_INTERNAL_API
+   static nsresult GetFile(nsIFile** aResult) {
+     nsCOMPtr<nsIFile> lf;
+ #  ifdef XP_WIN
+     wchar_t exePath[MAXPATHLEN];
+     nsresult rv = GetW(exePath);
+ #  else
+     char exePath[MAXPATHLEN];
diff --git a/app/win/zotero.exe.tar.xz b/app/win/zotero.exe.tar.xz
index 8498d348a0..eaf36223a3 100644
--- a/app/win/zotero.exe.tar.xz
+++ b/app/win/zotero.exe.tar.xz
@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:3eac8ba79ffd188c0175d70651533fd16efcd415e0761b8223023026380efec5
-size 364660
+oid sha256:601b33fd33765e0c29ed347c47cae850fce1f13e85f109e6a9ed8c9e8b564615
+size 421268