diff --git a/builtins-test-intrinsics/src/main.rs b/builtins-test-intrinsics/src/main.rs
index 21d0a083..a4fbfa0b 100644
--- a/builtins-test-intrinsics/src/main.rs
+++ b/builtins-test-intrinsics/src/main.rs
@@ -13,6 +13,8 @@
 #![no_std]
 #![no_main]
 
+// Ensure this `compiler_builtins` gets used, rather than the version injected from the sysroot.
+extern crate compiler_builtins;
 extern crate panic_handler;
 
 #[cfg(all(not(thumb), not(windows), not(target_arch = "wasm32")))]
@@ -592,7 +594,8 @@ fn run() {
     bb(floatunsitf(bb(2)));
     bb(floatuntidf(bb(2)));
     bb(floatuntisf(bb(2)));
-    #[cfg(f128_enabled)]
+    // FIXME(windows): segfault on Windows
+    #[cfg(all(f128_enabled, not(windows)))]
     bb(floatuntitf(bb(2)));
     #[cfg(f128_enabled)]
     bb(gttf(bb(2.), bb(2.)));
@@ -650,14 +653,14 @@ fn something_with_a_dtor(f: &dyn Fn()) {
 
 #[no_mangle]
 #[cfg(not(thumb))]
-fn main(_argc: core::ffi::c_int, _argv: *const *const u8) -> core::ffi::c_int {
+extern "C" fn main(_argc: core::ffi::c_int, _argv: *const *const u8) -> core::ffi::c_int {
     run();
     0
 }
 
 #[no_mangle]
 #[cfg(thumb)]
-pub fn _start() -> ! {
+extern "C" fn _start() -> ! {
     run();
     loop {}
 }
diff --git a/ci/run.sh b/ci/run.sh
index 9abbf25a..2d22a298 100755
--- a/ci/run.sh
+++ b/ci/run.sh
@@ -120,15 +120,21 @@ done
 
 rm -f "${rlib_paths[@]}"
 
-build_intrinsics_test() {
-    cargo build --target "$target" -v --package builtins-test-intrinsics "$@"
+run_intrinsics_test() {
+    if [ "${NO_STD:-}" = "1" ]; then
+        cmd=build
+    else
+        cmd=run
+    fi
+
+    cargo "$cmd" --target "$target" -v --package builtins-test-intrinsics "$@"
 }
 
 # Verify that we haven't dropped any intrinsics/symbols
-build_intrinsics_test
-build_intrinsics_test --release
-build_intrinsics_test --features c
-build_intrinsics_test --features c --release
+run_intrinsics_test
+run_intrinsics_test --release
+run_intrinsics_test --features c
+run_intrinsics_test --features c --release
 
 # Verify that there are no undefined symbols to `panic` within our
 # implementations