diff --git a/gui/apps/2048.cpp b/gui/apps/2048.cpp
index 039981f0..241cdfa0 100644
--- a/gui/apps/2048.cpp
+++ b/gui/apps/2048.cpp
@@ -1,4 +1,4 @@
-#include <luna/String.h>
+#include <luna/RefString.h>
 #include <luna/Utf8.h>
 #include <stdlib.h>
 #include <time.h>
@@ -325,7 +325,7 @@ class GameWidget final : public ui::Widget
 
         canvas.fill(colors[tile.color]);
 
-        auto fmt = TRY(String::format("%d"_sv, tile.number));
+        auto fmt = TRY(RefString::format("%d"_sv, tile.number));
 
         auto font = ui::Font::default_bold_font();
         auto rect = ui::align({ 0, 0, canvas.width, canvas.height },
diff --git a/gui/loginui.cpp b/gui/loginui.cpp
index 66d69818..fd81b0b2 100644
--- a/gui/loginui.cpp
+++ b/gui/loginui.cpp
@@ -7,7 +7,7 @@
  *
  */
 
-#include <luna/String.h>
+#include <luna/RefString.h>
 #include <os/ArgumentParser.h>
 #include <os/Config.h>
 #include <os/File.h>
@@ -68,7 +68,7 @@ Result<int> luna_main(int argc, char** argv)
 
         if (!username.is_empty())
         {
-            auto flag = String::format("--user=%s"_sv, username.chars()).release_value();
+            auto flag = RefString::format("--user=%s"_sv, username.chars()).release_value();
 
             StringView startui_command[] = { "/usr/bin/startui", flag.view() };
             os::Process::exec(startui_command[0], Slice<StringView>(startui_command, 2));
@@ -118,7 +118,7 @@ Result<int> luna_main(int argc, char** argv)
             stage = Stage::PasswordInput;
             label.set_text("Password:");
 
-            String title = String::format("Log in: %s"_sv, data.chars()).release_value();
+            RefString title = RefString::format("Log in: %s"_sv, data.chars()).release_value();
             window->set_title(title.view());
 
             input.clear();
@@ -160,7 +160,7 @@ Result<int> luna_main(int argc, char** argv)
                 return;
             }
 
-            auto flag = String::format("--user=%s"_sv, pw->pw_name).release_value();
+            auto flag = RefString::format("--user=%s"_sv, pw->pw_name).release_value();
 
             StringView startui_command[] = { "/usr/bin/startui", flag.view() };
             os::Process::exec(startui_command[0], Slice<StringView>(startui_command, 2));