diff --git a/Userland/Services/WindowServer/ConnectionFromClient.cpp b/Userland/Services/WindowServer/ConnectionFromClient.cpp
index 0adbe0d78f..e4f4353574 100644
--- a/Userland/Services/WindowServer/ConnectionFromClient.cpp
+++ b/Userland/Services/WindowServer/ConnectionFromClient.cpp
@@ -467,6 +467,36 @@ Messages::WindowServer::GetWindowRectResponse ConnectionFromClient::get_window_r
     return it->value->rect();
 }
 
+static Gfx::IntSize calculate_minimum_size_for_window(Window const& window)
+{
+    // NOTE: Windows with a title bar have a minimum size enforced by the system,
+    //       because we want to always keep their title buttons accessible.
+    if (window.type() == WindowType::Normal || window.type() == WindowType::ToolWindow) {
+        auto palette = WindowManager::the().palette();
+
+        int required_width = 0;
+        // Padding on left and right of window title content.
+        // FIXME: This seems like it should be defined in the theme.
+        required_width += 2 + 2;
+        // App icon
+        required_width += 16;
+        // Padding between icon and buttons
+        required_width += 2;
+        // Close button
+        required_width += palette.window_title_button_width();
+        // Maximize button
+        if (window.is_resizable())
+            required_width += palette.window_title_button_width();
+        // Minimize button
+        if (window.is_minimizable())
+            required_width += palette.window_title_button_width();
+
+        return { required_width, 0 };
+    }
+
+    return { 0, 0 };
+}
+
 void ConnectionFromClient::set_window_minimum_size(i32 window_id, Gfx::IntSize const& size)
 {
     auto it = m_windows.find(window_id);
@@ -480,7 +510,9 @@ void ConnectionFromClient::set_window_minimum_size(i32 window_id, Gfx::IntSize c
         return;
     }
 
-    window.set_minimum_size(size);
+    auto system_window_minimum_size = calculate_minimum_size_for_window(window);
+    window.set_minimum_size({ max(size.width(), system_window_minimum_size.width()),
+        max(size.height(), system_window_minimum_size.height()) });
 
     if (window.width() < window.minimum_size().width() || window.height() < window.minimum_size().height()) {
         // New minimum size is larger than the current window size, resize accordingly.
@@ -569,7 +601,9 @@ void ConnectionFromClient::create_window(i32 window_id, Gfx::IntRect const& rect
             new_rect = { WindowManager::the().get_recommended_window_position({ 100, 100 }), rect.size() };
             window->set_default_positioned(true);
         }
-        window->set_minimum_size(minimum_size);
+        auto system_window_minimum_size = calculate_minimum_size_for_window(window);
+        window->set_minimum_size({ max(minimum_size.width(), system_window_minimum_size.width()),
+            max(minimum_size.height(), system_window_minimum_size.height()) });
         bool did_size_clamp = window->apply_minimum_size(new_rect);
         window->set_rect(new_rect);
         window->nudge_into_desktop(nullptr);
@@ -1284,4 +1318,29 @@ void ConnectionFromClient::remove_window_stealing(i32 window_id)
     window->remove_all_stealing();
 }
 
+void ConnectionFromClient::notify_about_theme_change()
+{
+    // Recalculate minimum size for each window, using the new theme metrics.
+    // FIXME: We only ever increase the minimum size, which means that if you go from a theme with large buttons
+    //        (eg Basalt) to one with smaller buttons (eg Default) then the minimum size will remain large. This
+    //        only happens with pre-existing windows, and it's unlikely that you will ever have windows that are
+    //        so small, so it's probably fine, but it is technically a bug. :^)
+    for_each_window([](auto& window) -> IterationDecision {
+        auto system_window_minimum_size = calculate_minimum_size_for_window(window);
+
+        auto old_minimum_size = window.minimum_size();
+        auto new_rect = window.rect();
+
+        window.set_minimum_size({ max(old_minimum_size.width(), system_window_minimum_size.width()),
+            max(old_minimum_size.height(), system_window_minimum_size.height()) });
+        if (window.apply_minimum_size(new_rect)) {
+            window.set_rect(new_rect);
+            window.refresh_client_size();
+        }
+
+        return IterationDecision::Continue;
+    });
+    async_update_system_theme(Gfx::current_system_theme_buffer());
+}
+
 }
diff --git a/Userland/Services/WindowServer/ConnectionFromClient.h b/Userland/Services/WindowServer/ConnectionFromClient.h
index d0184b2805..0b8e4bf1fb 100644
--- a/Userland/Services/WindowServer/ConnectionFromClient.h
+++ b/Userland/Services/WindowServer/ConnectionFromClient.h
@@ -80,6 +80,8 @@ public:
 
     void notify_display_link(Badge<Compositor>);
 
+    void notify_about_theme_change();
+
 private:
     explicit ConnectionFromClient(NonnullOwnPtr<Core::Stream::LocalSocket>, int client_id);
 
diff --git a/Userland/Services/WindowServer/WindowManager.cpp b/Userland/Services/WindowServer/WindowManager.cpp
index 5635f096d9..1c66c95a01 100644
--- a/Userland/Services/WindowServer/WindowManager.cpp
+++ b/Userland/Services/WindowServer/WindowManager.cpp
@@ -2099,7 +2099,7 @@ void WindowManager::invalidate_after_theme_or_font_change()
         return IterationDecision::Continue;
     });
     ConnectionFromClient::for_each_client([&](ConnectionFromClient& client) {
-        client.async_update_system_theme(Gfx::current_system_theme_buffer());
+        client.notify_about_theme_change();
     });
     MenuManager::the().did_change_theme();
     AppletManager::the().did_change_theme();