diff --git a/emus/host/time.zig b/emus/host/time.zig
index 6b926eb..e5cf6a3 100644
--- a/emus/host/time.zig
+++ b/emus/host/time.zig
@@ -41,6 +41,7 @@ pub fn after(micro_seconds: u64) bool {
 
 // a helper which triggers an action once after a delay
 pub const Once = struct {
+    elapsed_us: u64 = 0,
     delay_us: u64,
     triggered: bool,
 
@@ -51,8 +52,9 @@ pub const Once = struct {
         };
     }
 
-    pub fn once(self: *Once) bool {
-        if (!self.triggered and after(self.delay_us)) {
+    pub fn once(self: *Once, delta_us: u64) bool {
+        self.elapsed_us +%= delta_us;
+        if (!self.triggered and (self.elapsed_us >= self.delay_us)) {
             self.triggered = true;
             return true;
         } else {
diff --git a/emus/kc85/kc85.zig b/emus/kc85/kc85.zig
index 2e2a747..688ec91 100644
--- a/emus/kc85/kc85.zig
+++ b/emus/kc85/kc85.zig
@@ -85,7 +85,7 @@ export fn frame() void {
             .emu_stats = host.prof.stats(.EMU),
         },
     });
-    if (file_loaded.once()) {
+    if (file_loaded.once(frame_time_us)) {
         if (args.file_data) |file_data| {
             sys.load(.{ .data = file_data, .start = true, .patch = .{ .func = patch } }) catch |err| {
                 print("Failed to load file into emulator with {}", .{err});