diff --git a/Userland/Libraries/LibGUI/FileSystemModel.cpp b/Userland/Libraries/LibGUI/FileSystemModel.cpp
index 4b63d81805..f6c7cea890 100644
--- a/Userland/Libraries/LibGUI/FileSystemModel.cpp
+++ b/Userland/Libraries/LibGUI/FileSystemModel.cpp
@@ -268,20 +268,19 @@ static String permission_string(mode_t mode)
     else
         builder.append("?");
 
-    builder.appendf("%c%c%c%c%c%c%c%c",
-        mode & S_IRUSR ? 'r' : '-',
-        mode & S_IWUSR ? 'w' : '-',
-        mode & S_ISUID ? 's' : (mode & S_IXUSR ? 'x' : '-'),
-        mode & S_IRGRP ? 'r' : '-',
-        mode & S_IWGRP ? 'w' : '-',
-        mode & S_ISGID ? 's' : (mode & S_IXGRP ? 'x' : '-'),
-        mode & S_IROTH ? 'r' : '-',
-        mode & S_IWOTH ? 'w' : '-');
+    builder.append(mode & S_IRUSR ? 'r' : '-');
+    builder.append(mode & S_IWUSR ? 'w' : '-');
+    builder.append(mode & S_ISUID ? 's' : (mode & S_IXUSR ? 'x' : '-'));
+    builder.append(mode & S_IRGRP ? 'r' : '-');
+    builder.append(mode & S_IWGRP ? 'w' : '-');
+    builder.append(mode & S_ISGID ? 's' : (mode & S_IXGRP ? 'x' : '-'));
+    builder.append(mode & S_IROTH ? 'r' : '-');
+    builder.append(mode & S_IWOTH ? 'w' : '-');
 
     if (mode & S_ISVTX)
-        builder.append("t");
+        builder.append('t');
     else
-        builder.appendf("%c", mode & S_IXOTH ? 'x' : '-');
+        builder.append(mode & S_IXOTH ? 'x' : '-');
     return builder.to_string();
 }
 
diff --git a/Userland/Libraries/LibGUI/Progressbar.cpp b/Userland/Libraries/LibGUI/Progressbar.cpp
index df5300ac30..dcdd409142 100644
--- a/Userland/Libraries/LibGUI/Progressbar.cpp
+++ b/Userland/Libraries/LibGUI/Progressbar.cpp
@@ -66,9 +66,9 @@ void Progressbar::paint_event(PaintEvent& event)
         if (m_format == Format::Percentage) {
             float range_size = m_max - m_min;
             float progress = (m_value - m_min) / range_size;
-            builder.appendf("%d%%", (int)(progress * 100));
+            builder.appendff("{}%", (int)(progress * 100));
         } else if (m_format == Format::ValueSlashMax) {
-            builder.appendf("%d/%d", m_value, m_max);
+            builder.appendff("{}/{}", m_value, m_max);
         }
         progress_text = builder.to_string();
     }