diff --git a/.circleci/config.yml b/.circleci/config.yml
new file mode 100644
index 00000000..6ad50a8a
--- /dev/null
+++ b/.circleci/config.yml
@@ -0,0 +1,22 @@
+version: 2.1
+
+jobs:
+  test-io-uring-features:
+    machine:
+      image: ubuntu-2004:202107-02
+    resource_class: large
+    environment:
+      CI: '1'
+      CARGO_INCREMENTAL: '0'
+      RUST_BACKTRACE: '1'
+    steps:
+      - checkout
+      - run: uname -a
+      - run: apt-get update; apt-get install -y liburing-dev
+      - run: cargo test -p=actix-rt --features=io-uring
+      - run: cargo test -p=actix-server --features=io-uring
+
+workflows:
+  test:
+    jobs:
+      - test-io-uring-features
diff --git a/actix-rt/src/system.rs b/actix-rt/src/system.rs
index e32d6209..6c089dda 100644
--- a/actix-rt/src/system.rs
+++ b/actix-rt/src/system.rs
@@ -175,9 +175,9 @@ impl System {
     }
 }
 
-#[cfg(not(feature = "io-uring"))]
 /// Runner that keeps a [System]'s event loop alive until stop message is received.
-#[must_use = "A SystemRunner does nothing unless `run` is called."]
+#[cfg(not(feature = "io-uring"))]
+#[must_use = "A SystemRunner does nothing unless `run` or `block_on` is called."]
 #[derive(Debug)]
 pub struct SystemRunner {
     rt: crate::runtime::Runtime,
@@ -216,9 +216,9 @@ impl SystemRunner {
     }
 }
 
-#[cfg(feature = "io-uring")]
 /// Runner that keeps a [System]'s event loop alive until stop message is received.
-#[must_use = "A SystemRunner does nothing unless `run` is called."]
+#[cfg(feature = "io-uring")]
+#[must_use = "A SystemRunner does nothing unless `run` or `block_on` is called."]
 #[derive(Debug)]
 pub struct SystemRunner;