diff --git a/Base/res/icons/16x16/window-close-modified-2x.png b/Base/res/icons/16x16/window-close-modified-2x.png
new file mode 100644
index 00000000000..f714d1a2e63
Binary files /dev/null and b/Base/res/icons/16x16/window-close-modified-2x.png differ
diff --git a/Base/res/icons/16x16/window-close-modified.png b/Base/res/icons/16x16/window-close-modified.png
new file mode 100644
index 00000000000..95657d3e4c4
Binary files /dev/null and b/Base/res/icons/16x16/window-close-modified.png differ
diff --git a/Base/res/icons/themes/Coffee/16x16/window-close-modified.png b/Base/res/icons/themes/Coffee/16x16/window-close-modified.png
new file mode 100644
index 00000000000..aa16575f356
Binary files /dev/null and b/Base/res/icons/themes/Coffee/16x16/window-close-modified.png differ
diff --git a/Base/res/icons/themes/Redmond/16x16/window-close-modified.png b/Base/res/icons/themes/Redmond/16x16/window-close-modified.png
new file mode 100644
index 00000000000..7eaaf706770
Binary files /dev/null and b/Base/res/icons/themes/Redmond/16x16/window-close-modified.png differ
diff --git a/Base/res/icons/themes/Sunshine/16x16/window-close-modified.png b/Base/res/icons/themes/Sunshine/16x16/window-close-modified.png
new file mode 100644
index 00000000000..4e79eba6d36
Binary files /dev/null and b/Base/res/icons/themes/Sunshine/16x16/window-close-modified.png differ
diff --git a/Userland/Services/WindowServer/Window.cpp b/Userland/Services/WindowServer/Window.cpp
index 1d7a6687419..8ffc784d5e9 100644
--- a/Userland/Services/WindowServer/Window.cpp
+++ b/Userland/Services/WindowServer/Window.cpp
@@ -998,6 +998,7 @@ void Window::set_modified(bool modified)
         return;
 
     m_modified = modified;
+    frame().set_button_icons();
     frame().invalidate_titlebar();
 }
 
diff --git a/Userland/Services/WindowServer/Window.h b/Userland/Services/WindowServer/Window.h
index c2db7b8bb3b..a1785bf6482 100644
--- a/Userland/Services/WindowServer/Window.h
+++ b/Userland/Services/WindowServer/Window.h
@@ -371,6 +371,7 @@ private:
     bool m_invalidated_all { true };
     bool m_invalidated_frame { true };
     bool m_hit_testing_enabled { true };
+    bool m_modified { false };
     WindowTileType m_tiled { WindowTileType::None };
     Gfx::IntRect m_untiled_rect;
     bool m_occluded { false };
@@ -400,7 +401,6 @@ private:
     int m_minimize_animation_step { -1 };
     Optional<int> m_progress;
     bool m_should_show_menubar { true };
-    bool m_modified { false };
 };
 
 }
diff --git a/Userland/Services/WindowServer/WindowFrame.cpp b/Userland/Services/WindowServer/WindowFrame.cpp
index 21e4136b1fa..167890fef20 100644
--- a/Userland/Services/WindowServer/WindowFrame.cpp
+++ b/Userland/Services/WindowServer/WindowFrame.cpp
@@ -38,6 +38,7 @@ static Gfx::Bitmap* s_minimize_icon;
 static Gfx::Bitmap* s_maximize_icon;
 static Gfx::Bitmap* s_restore_icon;
 static Gfx::Bitmap* s_close_icon;
+static Gfx::Bitmap* s_close_modified_icon;
 
 static String s_last_title_button_icons_path;
 static int s_last_title_button_icons_scale;
@@ -102,7 +103,7 @@ void WindowFrame::set_button_icons()
     if (m_window.is_frameless())
         return;
 
-    m_close_button->set_icon(*s_close_icon);
+    m_close_button->set_icon(m_window.is_modified() ? *s_close_modified_icon : *s_close_icon);
     if (m_window.is_minimizable())
         m_minimize_button->set_icon(*s_minimize_icon);
     if (m_window.is_resizable())
@@ -151,6 +152,15 @@ void WindowFrame::reload_config()
             s_close_icon = Gfx::Bitmap::load_from_file("/res/icons/16x16/window-close.png", icons_scale).leak_ref();
         full_path.clear();
     }
+    if (!s_close_modified_icon || s_last_title_button_icons_path != icons_path || s_last_title_button_icons_scale != icons_scale) {
+        full_path.append(icons_path);
+        full_path.append("window-close-modified.png");
+        if (s_close_modified_icon)
+            s_close_modified_icon->unref();
+        if (!(s_close_modified_icon = Gfx::Bitmap::load_from_file(full_path.to_string(), icons_scale).leak_ref()))
+            s_close_modified_icon = Gfx::Bitmap::load_from_file("/res/icons/16x16/window-close-modified.png", icons_scale).leak_ref();
+        full_path.clear();
+    }
 
     s_last_title_button_icons_path = icons_path;
     s_last_title_button_icons_scale = icons_scale;