diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 875c3f39d1..02b7f4fadb 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -25,7 +25,7 @@ jobs:
         uses: actions-rs/toolchain@v1
         with:
           profile: minimal
-          toolchain: stable
+          toolchain: nightly
           override: true
           components: rustfmt
 
@@ -49,7 +49,7 @@ jobs:
           - thumbv6m-none-eabi
           - x86_64-unknown-linux-gnu
         toolchain:
-          - stable
+          - nightly
     steps:
       - name: Checkout
         uses: actions/checkout@v2
@@ -82,12 +82,13 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v2
 
-      - name: Install Rust stable
+      - name: Install Rust nightly
         uses: actions-rs/toolchain@v1
         with:
-          toolchain: stable
+          toolchain: nightly
           target: x86_64-unknown-linux-gnu
           override: true
+          components: clippy
 
       - name: Fail on warnings
         run: sed -i 's,//deny_warnings_placeholder_for_ci,#![deny(warnings)],' src/lib.rs macros/src/lib.rs
@@ -111,7 +112,7 @@ jobs:
           - thumbv7m-none-eabi
           - thumbv6m-none-eabi
         toolchain:
-          - stable
+          - nightly
     steps:
       - name: Checkout
         uses: actions/checkout@v2
@@ -144,7 +145,7 @@ jobs:
           - thumbv7m-none-eabi
           - thumbv6m-none-eabi
         toolchain:
-          - stable
+          - nightly
     steps:
       - name: Checkout
         uses: actions/checkout@v2
@@ -188,7 +189,7 @@ jobs:
         target:
           - x86_64-unknown-linux-gnu
         toolchain:
-          - stable
+          - nightly
     steps:
       - name: Checkout
         uses: actions/checkout@v2
@@ -224,7 +225,7 @@ jobs:
       - name: Install Rust
         uses: actions-rs/toolchain@v1
         with:
-          toolchain: stable
+          toolchain: nightly
           target: x86_64-unknown-linux-gnu
           override: true
 
@@ -252,7 +253,7 @@ jobs:
       - name: Install Rust
         uses: actions-rs/toolchain@v1
         with:
-          toolchain: stable
+          toolchain: nightly
           target: x86_64-unknown-linux-gnu
           override: true
 
diff --git a/ci/expected/async-delay.run b/ci/expected/async-delay.run
new file mode 100644
index 0000000000..61852abfd9
--- /dev/null
+++ b/ci/expected/async-delay.run
@@ -0,0 +1,7 @@
+init
+hello from bar
+hello from baz
+hello from foo
+bye from foo
+bye from bar
+bye from baz
diff --git a/ci/expected/async-infinite-loop.run b/ci/expected/async-infinite-loop.run
new file mode 100644
index 0000000000..f9fd4e494c
--- /dev/null
+++ b/ci/expected/async-infinite-loop.run
@@ -0,0 +1,6 @@
+init
+hello from async 0
+hello from async 1
+hello from async 2
+hello from async 3
+hello from async 4
diff --git a/ci/expected/async-task-multiple-prios.run b/ci/expected/async-task-multiple-prios.run
new file mode 100644
index 0000000000..9b0f53365b
--- /dev/null
+++ b/ci/expected/async-task-multiple-prios.run
@@ -0,0 +1,5 @@
+init
+hello from normal 2
+hello from async 2
+hello from normal 1
+hello from async 1
diff --git a/ci/expected/async-task.run b/ci/expected/async-task.run
new file mode 100644
index 0000000000..f7ce3a6065
--- /dev/null
+++ b/ci/expected/async-task.run
@@ -0,0 +1,3 @@
+init
+hello from normal
+hello from async
diff --git a/ci/expected/async-timeout.run b/ci/expected/async-timeout.run
new file mode 100644
index 0000000000..a8074230ee
--- /dev/null
+++ b/ci/expected/async-timeout.run
@@ -0,0 +1,5 @@
+init
+hello from bar
+hello from foo
+foo no timeout
+bar timeout
diff --git a/macros/src/check.rs b/macros/src/check.rs
index 4b360738f5..74df688c58 100644
--- a/macros/src/check.rs
+++ b/macros/src/check.rs
@@ -43,7 +43,7 @@ pub fn app(app: &App, _analysis: &Analysis) -> parse::Result<Extra> {
     let need = priorities
         .iter()
         // Only count if not 0
-        .filter_map(|prio| if *prio > 0 { Some(prio) } else { None })
+        .filter(|prio| **prio > 0)
         .count();
     let given = app.args.extern_interrupts.len();
     if need > given {
diff --git a/macros/src/codegen/dispatchers.rs b/macros/src/codegen/dispatchers.rs
index 62df429370..6b241140a7 100644
--- a/macros/src/codegen/dispatchers.rs
+++ b/macros/src/codegen/dispatchers.rs
@@ -183,14 +183,11 @@ pub fn codegen(app: &App, analysis: &Analysis, extra: &Extra) -> Vec<TokenStream
             }
         ));
 
-        for name in channel.tasks.iter().filter_map(|name| {
-            let task = &app.software_tasks[name];
-            if task.is_async {
-                Some(name)
-            } else {
-                None
-            }
-        }) {
+        for name in channel
+            .tasks
+            .iter()
+            .filter(|name| app.software_tasks[*name].is_async)
+        {
             let exec_name = util::internal_task_ident(name, "EXEC");
 
             let executor_run_ident = util::executor_run_ident(name);