diff --git a/crates/bevy_core/src/lib.rs b/crates/bevy_core/src/lib.rs
index 5a039fb92f..25b2c6a3f7 100644
--- a/crates/bevy_core/src/lib.rs
+++ b/crates/bevy_core/src/lib.rs
@@ -4,6 +4,7 @@ pub mod transform;
 
 use bevy_app::{stage, AppBuilder, AppPlugin};
 use bevy_transform::transform_system_bundle;
+use legion::prelude::IntoSystem;
 use time::{start_timer_system, stop_timer_system};
 
 #[derive(Default)]
@@ -16,7 +17,7 @@ impl AppPlugin for CorePlugin {
         }
 
         app.add_resource(time::Time::new())
-            .add_system_to_stage(stage::FIRST, start_timer_system())
-            .add_system_to_stage(stage::LAST, stop_timer_system());
+            .add_system_to_stage(stage::FIRST, start_timer_system.system())
+            .add_system_to_stage(stage::LAST, stop_timer_system.system());
     }
 }
diff --git a/crates/bevy_core/src/time.rs b/crates/bevy_core/src/time.rs
index 46f82ccda1..f73fb6e0aa 100644
--- a/crates/bevy_core/src/time.rs
+++ b/crates/bevy_core/src/time.rs
@@ -30,18 +30,10 @@ impl Time {
     }
 }
 
-pub fn start_timer_system() -> Box<dyn Schedulable> {
-    SystemBuilder::new("start_timer")
-        .write_resource::<Time>()
-        .build(|_, _, time, _| {
-            time.start();
-        })
+pub fn start_timer_system(mut time: ResourceMut<Time>) {
+    time.start();
 }
 
-pub fn stop_timer_system() -> Box<dyn Schedulable> {
-    SystemBuilder::new("stop_timer")
-        .write_resource::<Time>()
-        .build(|_, _, time, _| {
-            time.stop();
-        })
-}
+pub fn stop_timer_system(mut time: ResourceMut<Time>) {
+    time.stop();
+}
\ No newline at end of file
diff --git a/crates/bevy_diagnostic/src/diagnostics.rs b/crates/bevy_diagnostic/src/diagnostics.rs
index 2440ac3891..f77f86f8db 100644
--- a/crates/bevy_diagnostic/src/diagnostics.rs
+++ b/crates/bevy_diagnostic/src/diagnostics.rs
@@ -12,82 +12,83 @@ pub const FRAME_TIME: DiagnosticId = DiagnosticId(Uuid::from_bytes([
     216, 184, 55, 12, 28, 116, 69, 201, 187, 137, 176, 77, 83, 89, 251, 241,
 ]));
 
+pub fn setup_frame_time_diagnostic_system(mut diagnostics: ResourceMut<Diagnostics>) {
+    diagnostics.add(Diagnostic::new(FRAME_TIME, "frame_time", 10));
+    diagnostics.add(Diagnostic::new(FPS, "fps", 10));
+}
+
 pub fn frame_time_diagnostic_system(
-    resources: &Resources,
-    max_history_length: usize,
-) -> Box<dyn Schedulable> {
-    let mut diagnostics = resources.get_mut::<Diagnostics>().unwrap();
-    diagnostics.add(Diagnostic::new(
-        FRAME_TIME,
-        "frame_time",
-        max_history_length,
-    ));
-    diagnostics.add(Diagnostic::new(FPS, "fps", max_history_length));
-    SystemBuilder::new("frame_time_diagnostic")
-        .read_resource::<Time>()
-        .write_resource::<Diagnostics>()
-        .build(move |_, _world, (time, ref mut diagnostics), _queries| {
-            if time.delta_seconds_f64 == 0.0 {
-                return;
-            }
+    mut diagnostics: ResourceMut<Diagnostics>,
+    time: Resource<Time>,
+) {
+    if time.delta_seconds_f64 == 0.0 {
+        return;
+    }
 
-            diagnostics.add_measurement(FRAME_TIME, time.delta_seconds_f64);
-            if let Some(fps) = diagnostics
-                .get(FRAME_TIME)
-                .and_then(|frame_time_diagnostic| {
-                    frame_time_diagnostic
-                        .average()
-                        .and_then(|frame_time_average| {
-                            if frame_time_average > 0.0 {
-                                Some(1.0 / frame_time_average)
-                            } else {
-                                None
-                            }
-                        })
-                })
-            {
-                diagnostics.add_measurement(FPS, fps);
-            }
-        })
-}
-
-pub fn print_diagnostics_system(wait: Duration) -> Box<dyn Schedulable> {
-    let mut elasped = 0.0;
-    let wait_seconds = wait.as_secs_f64();
-    SystemBuilder::new("print_diagnostics")
-        .read_resource::<Time>()
-        .read_resource::<Diagnostics>()
-        .build(move |_, _world, (time, diagnostics), _queries| {
-            elasped += time.delta_seconds_f64;
-            if elasped >= wait_seconds {
-                elasped = 0.0;
-                for diagnostic in diagnostics.iter() {
-                    if let Some(value) = diagnostic.value() {
-                        print!("{:<10}: {:<9.6}", diagnostic.name, value);
-                        if let Some(average) = diagnostic.average() {
-                            print!("  (avg {:.6})", average);
-                        }
-
-                        println!("\n");
+    diagnostics.add_measurement(FRAME_TIME, time.delta_seconds_f64);
+    if let Some(fps) = diagnostics
+        .get(FRAME_TIME)
+        .and_then(|frame_time_diagnostic| {
+            frame_time_diagnostic
+                .average()
+                .and_then(|frame_time_average| {
+                    if frame_time_average > 0.0 {
+                        Some(1.0 / frame_time_average)
+                    } else {
+                        None
                     }
-                }
-            }
+                })
         })
+    {
+        diagnostics.add_measurement(FPS, fps);
+    }
 }
 
-pub fn print_diagnostics_debug_system(wait: Duration) -> Box<dyn Schedulable> {
-    let mut elasped = 0.0;
-    let wait_seconds = wait.as_secs_f64();
-    SystemBuilder::new("print_diagnostics_debug")
-        .read_resource::<Time>()
-        .read_resource::<Diagnostics>()
-        .build(move |_, _world, (time, diagnostics), _queries| {
-            elasped += time.delta_seconds_f64;
-            if elasped >= wait_seconds {
-                elasped = 0.0;
-                for diagnostic in diagnostics.iter() {
-                    println!("{:#?}\n", diagnostic);
-                }
-            }
-        })
+pub struct PrintDiagnosticsState {
+    elapsed: f64,
+    wait_seconds: f64,
+}
+
+impl PrintDiagnosticsState {
+    pub fn new(wait: Duration) -> Self {
+        PrintDiagnosticsState {
+            elapsed: 0.,
+            wait_seconds: wait.as_secs_f64(),
+        }
+    }
+}
+
+pub fn print_diagnostics_system(
+    mut state: ResourceMut<PrintDiagnosticsState>,
+    time: Resource<Time>,
+    diagnostics: Resource<Diagnostics>,
+) {
+    state.elapsed += time.delta_seconds_f64;
+    if state.elapsed >= state.wait_seconds {
+        state.elapsed = 0.0;
+        for diagnostic in diagnostics.iter() {
+            if let Some(value) = diagnostic.value() {
+                print!("{:<10}: {:<9.6}", diagnostic.name, value);
+                if let Some(average) = diagnostic.average() {
+                    print!("  (avg {:.6})", average);
+                }
+
+                println!("\n");
+            }
+        }
+    }
+}
+
+pub fn print_diagnostics_debug_system(
+    mut state: ResourceMut<PrintDiagnosticsState>,
+    time: Resource<Time>,
+    diagnostics: Resource<Diagnostics>,
+) {
+    state.elapsed += time.delta_seconds_f64;
+    if state.elapsed >= state.wait_seconds {
+        state.elapsed = 0.0;
+        for diagnostic in diagnostics.iter() {
+            println!("{:#?}\n", diagnostic);
+        }
+    }
 }
diff --git a/crates/bevy_diagnostic/src/lib.rs b/crates/bevy_diagnostic/src/lib.rs
index b3681d21df..691b319c91 100644
--- a/crates/bevy_diagnostic/src/lib.rs
+++ b/crates/bevy_diagnostic/src/lib.rs
@@ -3,7 +3,11 @@ pub mod diagnostics;
 pub use diagnostic::*;
 
 use bevy_app::{AppBuilder, AppPlugin};
-use diagnostics::{frame_time_diagnostic_system, print_diagnostics_system};
+use diagnostics::{
+    frame_time_diagnostic_system, print_diagnostics_system, setup_frame_time_diagnostic_system,
+    PrintDiagnosticsState,
+};
+use legion::prelude::IntoSystem;
 use std::time::Duration;
 
 pub struct DiagnosticsPlugin {
@@ -24,15 +28,15 @@ impl Default for DiagnosticsPlugin {
 
 impl AppPlugin for DiagnosticsPlugin {
     fn build(&self, app: &mut AppBuilder) {
-        app.add_resource(Diagnostics::default());
+        app.add_resource_init::<Diagnostics>();
         if self.add_defaults {
-            let frame_time_diagnostic_system =
-                { frame_time_diagnostic_system(app.resources_mut(), 10) };
-            app.add_system(frame_time_diagnostic_system);
+            app.add_startup_system(setup_frame_time_diagnostic_system.system())
+                .add_system(frame_time_diagnostic_system.system());
         }
 
         if self.print_diagnostics {
-            app.add_system(print_diagnostics_system(self.print_wait_duration));
+            app.add_resource(PrintDiagnosticsState::new(self.print_wait_duration))
+                .add_system(print_diagnostics_system.system());
         }
     }
 }