diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8f519e533..1a0c4323b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -110,6 +110,39 @@ jobs:
         command:  check
         args: --no-default-features --features alloc --target thumbv7m-none-eabi -Z avoid-dev-deps
 
+  cross:
+    name: Cross compile
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        target:
+          - i686-unknown-linux-gnu
+          - powerpc-unknown-linux-gnu
+          - powerpc64-unknown-linux-gnu
+          - mips-unknown-linux-gnu
+          - arm-linux-androideabi
+
+    steps:
+    - uses: actions/checkout@master
+
+    - name: Install nightly
+      uses: actions-rs/toolchain@v1
+      with:
+        toolchain: nightly
+        override: true
+
+    - name: Install cross
+      run: cargo install cross
+
+    - name: check
+      run: cross check --all --target ${{ matrix.target }}
+
+    - name: check unstable
+      run: cross check --all --features unstable --target ${{ matrix.target }}
+
+    - name: test
+      run: cross test --all --features unstable --target ${{ matrix.target }}
+
   check_fmt_and_docs:
     name: Checking fmt and docs
     runs-on: ubuntu-latest
diff --git a/Cargo.toml b/Cargo.toml
index 630b373a2..c6a10a20b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -68,6 +68,9 @@ pin-project-lite = { version = "0.1.4", optional = true }
 pin-utils = { version = "0.1.0-alpha.4", optional = true }
 slab = { version = "0.4.2", optional = true }
 
+# Devdepencency, but they are not allowed to be optional :/
+surf = { version = "1.0.3", optional = true }
+
 [target.'cfg(not(target_os = "unknown"))'.dependencies]
 smol = { version = "0.1.1", optional = true }
 
@@ -82,7 +85,6 @@ wasm-bindgen-test = "0.3.10"
 [dev-dependencies]
 femme = "1.3.0"
 rand = "0.7.3"
-surf = "1.0.3"
 tempdir = "0.3.7"
 futures = "0.3.4"
 rand_xorshift = "0.2.0"
@@ -94,3 +96,7 @@ required-features = ["unstable"]
 [[example]]
 name = "tcp-ipv4-and-6-echo"
 required-features = ["unstable"]
+
+[[example]]
+name = "surf-web"
+required-features = ["surf"]
\ No newline at end of file
diff --git a/src/task/task_id.rs b/src/task/task_id.rs
index 67eee154b..92c607c71 100644
--- a/src/task/task_id.rs
+++ b/src/task/task_id.rs
@@ -1,5 +1,5 @@
 use std::fmt;
-use std::sync::atomic::{AtomicU64, Ordering};
+use std::sync::atomic::{AtomicUsize, Ordering};
 
 /// A unique identifier for a task.
 ///
@@ -13,15 +13,16 @@ use std::sync::atomic::{AtomicU64, Ordering};
 /// })
 /// ```
 #[derive(Eq, PartialEq, Clone, Copy, Hash, Debug)]
-pub struct TaskId(pub(crate) u64);
+pub struct TaskId(pub(crate) usize);
 
 impl TaskId {
     /// Generates a new `TaskId`.
     pub(crate) fn generate() -> TaskId {
-        static COUNTER: AtomicU64 = AtomicU64::new(1);
+        // TODO: find a good version to emulate u64 atomics on 32 bit systems.
+        static COUNTER: AtomicUsize = AtomicUsize::new(1);
 
         let id = COUNTER.fetch_add(1, Ordering::Relaxed);
-        if id > u64::max_value() / 2 {
+        if id > usize::max_value() / 2 {
             std::process::abort();
         }
         TaskId(id)