diff --git a/Cargo.toml b/Cargo.toml
index e23c666..69b9c03 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -27,5 +27,9 @@ utest-cortex-m-qemu = { default-features = false, git = "https://github.com/japa
 utest-macros = { git = "https://github.com/japaric/utest" }
 
 
+[[example]]
+name = "intrinsics"
+required-features = ["c"]
+
 
 [workspace]
diff --git a/appveyor.yml b/appveyor.yml
index f5a4c62..2bef109 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -5,7 +5,7 @@ environment:
 
 install:
   - git submodule update --init
-  - curl -sSf -o rustup-init.exe https://win.rustup.rs
+  - appveyor-retry appveyor DownloadFile https://win.rustup.rs/ -FileName rustup-init.exe
   - rustup-init.exe --default-host x86_64-pc-windows-msvc --default-toolchain nightly -y
   - set PATH=%PATH%;C:\Users\appveyor\.cargo\bin
   - if "%TARGET%"=="i686-pc-windows-msvc" ( rustup target add %TARGET% )
@@ -18,4 +18,6 @@ test_script:
   - cargo build --target %TARGET%
   - cargo build --release --target %TARGET%
   - cargo test --no-default-features --features gen-tests --target %TARGET%
+  - cargo test --no-default-features --features "gen-tests c" --target %TARGET%
   - cargo test --no-default-features --features gen-tests --release --target %TARGET%
+  - cargo test --no-default-features --features "gen-tests c" --release --target %TARGET%
diff --git a/ci/run.sh b/ci/run.sh
index 4a28e8a..02b9bf1 100755
--- a/ci/run.sh
+++ b/ci/run.sh
@@ -34,7 +34,9 @@ case $1 in
         ;;
     *)
         cargo test --no-default-features --features gen-tests --target $1
+        cargo test --no-default-features --features 'gen-tests c' --target $1
         cargo test --no-default-features --features gen-tests --target $1 --release
+        cargo test --no-default-features --features 'gen-tests c' --target $1 --release
         ;;
 esac
 
diff --git a/examples/intrinsics.rs b/examples/intrinsics.rs
index 4c5c884..4015ac3 100644
--- a/examples/intrinsics.rs
+++ b/examples/intrinsics.rs
@@ -6,17 +6,17 @@
 #![allow(unused_features)]
 #![cfg_attr(thumb, no_main)]
 #![deny(dead_code)]
+#![feature(alloc_system)]
 #![feature(asm)]
 #![feature(compiler_builtins_lib)]
 #![feature(core_float)]
 #![feature(lang_items)]
-#![feature(libc)]
 #![feature(start)]
 #![feature(i128_type)]
 #![no_std]
 
 #[cfg(not(thumb))]
-extern crate libc;
+extern crate alloc_system;
 extern crate compiler_builtins;
 
 // NOTE cfg(not(thumbv6m)) means that the operation is not supported on ARMv6-M at all. Not even
@@ -27,7 +27,6 @@ extern crate compiler_builtins;
 // convention for its intrinsics that's different from other architectures; that's why some function
 // have an additional comment: the function name is the ARM name for the intrinsic and the comment
 // in the non-ARM name for the intrinsic.
-#[cfg(feature = "c")]
 mod intrinsics {
     use core::num::Float;
 
@@ -339,7 +338,6 @@ mod intrinsics {
     }
 }
 
-#[cfg(feature = "c")]
 fn run() {
     use intrinsics::*;
 
@@ -404,33 +402,20 @@ fn run() {
     bb(modti3(bb(2), bb(2)));
 }
 
-#[cfg(all(feature = "c", not(thumb)))]
+#[cfg(not(thumb))]
 #[start]
 fn main(_: isize, _: *const *const u8) -> isize {
     run();
-
     0
 }
 
-#[cfg(all(not(feature = "c"), not(thumb)))]
-#[start]
-fn main(_: isize, _: *const *const u8) -> isize {
-    0
-}
-
-#[cfg(all(feature = "c", thumb))]
+#[cfg(thumb)]
 #[no_mangle]
 pub fn _start() -> ! {
     run();
     loop {}
 }
 
-#[cfg(all(not(feature = "c"), thumb))]
-#[no_mangle]
-pub fn _start() -> ! {
-    loop {}
-}
-
 // ARM targets need these symbols
 #[no_mangle]
 pub fn __aeabi_unwind_cpp_pr0() {}
@@ -447,9 +432,11 @@ pub fn _Unwind_Resume() {}
 #[cfg(not(test))]
 #[lang = "eh_personality"]
 #[no_mangle]
+#[allow(private_no_mangle_fns)]
 extern "C" fn eh_personality() {}
 
 #[cfg(not(test))]
 #[lang = "panic_fmt"]
 #[no_mangle]
+#[allow(private_no_mangle_fns)]
 extern "C" fn panic_fmt() {}