diff --git a/CLI/cmux.swift b/CLI/cmux.swift
index 29b5608b..cc3b3faa 100644
--- a/CLI/cmux.swift
+++ b/CLI/cmux.swift
@@ -5996,10 +5996,11 @@ struct CMUXCLI {
 
     private func removingManagedThemeOverride(from contents: String) -> String {
         let pattern = #"(?ms)\n?# cmux themes start\n.*?\n# cmux themes end\n?"#
-        guard let range = contents.range(of: pattern, options: [.regularExpression]) else {
+        guard let regex = try? NSRegularExpression(pattern: pattern) else {
             return contents
         }
-        return contents.replacingCharacters(in: range, with: "")
+        let fullRange = NSRange(contents.startIndex..<contents.endIndex, in: contents)
+        return regex.stringByReplacingMatches(in: contents, options: [], range: fullRange, withTemplate: "")
     }
 
     private func reloadThemesIfPossible() -> ThemeReloadStatus {
diff --git a/ghostty b/ghostty
index 3ec087ad..80cca8a1 160000
--- a/ghostty
+++ b/ghostty
@@ -1 +1 @@
-Subproject commit 3ec087ad3481e61df170373c20f07162154abb29
+Subproject commit 80cca8a12ebd554953fc6b35235135a3e61fe20c