diff --git a/src/WindowManager.zig b/src/WindowManager.zig
index e5af03e..a6e9cbc 100644
--- a/src/WindowManager.zig
+++ b/src/WindowManager.zig
@@ -34,6 +34,14 @@ pub fn deinit(wm: *WindowManager) void {
 }
 
 pub fn start(wm: *WindowManager) !void {
+    try wm.discoverScreens();
+    try wm.registerWindows();
+
+    log.info("mimi is ready, listening for messages", .{});
+    pumpMessages();
+}
+
+fn discoverScreens(wm: *WindowManager) !void {
     var monitors: std.ArrayList(Monitor) = .empty;
     defer monitors.deinit(wm.allocator);
 
@@ -46,11 +54,13 @@ pub fn start(wm: *WindowManager) !void {
         return Error.NoMonitors;
     }
 
-    try wm.screens.ensureTotalCapacity(wm.allocator, monitors.items.len);
+    try wm.screens.ensureTotalCapacityPrecise(wm.allocator, monitors.items.len);
     for (monitors.items) |monitor| {
         wm.screens.appendAssumeCapacity(.init(monitor));
     }
+}
 
+fn registerWindows(wm: *WindowManager) !void {
     var windows: std.ArrayList(Window) = .empty;
     defer windows.deinit(wm.allocator);
 
@@ -59,13 +69,15 @@ pub fn start(wm: *WindowManager) !void {
     log.info("found {d} open window(s)", .{windows.items.len});
 
     for (windows.items) |window| {
-        const monitor: Monitor = window.monitor();
-        const screen: *Screen = wm.findScreen(monitor).?;
+        const screen: *Screen = wm.findScreen(window.monitor()) orelse {
+            log.debug("window on unknown monitor, skipping", .{});
+            continue;
+        };
         try screen.windows.append(wm.allocator, window);
     }
+}
 
-    log.info("mimi is ready, listening for messages", .{});
-
+fn pumpMessages() void {
     var msg: win32.ui.windows_and_messaging.MSG = undefined;
     while (win32.ui.windows_and_messaging.GetMessageW(&msg, null, 0, 0) != 0) {
         _ = win32.ui.windows_and_messaging.TranslateMessage(&msg);