diff --git a/src/bin/cargo-miri.rs b/src/bin/cargo-miri.rs
index 4c83c5bd3dc..2dc6eee5de9 100644
--- a/src/bin/cargo-miri.rs
+++ b/src/bin/cargo-miri.rs
@@ -155,6 +155,9 @@ fn setup(ask_user: bool) {
     File::create(dir.join("Xargo.toml")).unwrap()
         .write_all(br#"
 [dependencies.std]
+default_features = false
+# We need the `panic_unwind` feature because we use the `unwind` panic strategy.
+# Using `abort` works for libstd, but then libtest will not compile.
 features = ["panic_unwind"]
 
 [dependencies.test]
diff --git a/src/lib.rs b/src/lib.rs
index 9739a7a95b6..ec4e621a24a 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -310,26 +310,9 @@ impl<'a, 'mir, 'tcx> Machine<'a, 'mir, 'tcx> for Evaluator<'tcx> {
 
     const STATIC_KIND: Option<MiriMemoryKind> = Some(MiriMemoryKind::MutStatic);
 
+    #[inline(always)]
     fn enforce_validity(ecx: &EvalContext<'a, 'mir, 'tcx, Self>) -> bool {
-        if !ecx.machine.validate {
-            return false;
-        }
-
-        // Some functions are whitelisted until we figure out how to fix them.
-        // We walk up the stack a few frames to also cover their callees.
-        const WHITELIST: &[(&str, &str)] = &[
-            // Uses mem::uninitialized
-            ("std::sys::windows::mutex::Mutex::", ""),
-        ];
-        for frame in ecx.stack().iter()
-            .rev().take(3)
-        {
-            let name = frame.instance.to_string();
-            if WHITELIST.iter().any(|(prefix, suffix)| name.starts_with(prefix) && name.ends_with(suffix)) {
-                return false;
-            }
-        }
-        true
+        ecx.machine.validate
     }
 
     /// Returns Ok() when the function was handled, fail otherwise
diff --git a/tests/compiletest.rs b/tests/compiletest.rs
index de693bd4632..1c11d07c1bc 100644
--- a/tests/compiletest.rs
+++ b/tests/compiletest.rs
@@ -124,16 +124,33 @@ fn is_target_dir<P: Into<PathBuf>>(path: P) -> bool {
     path.metadata().map(|m| m.is_dir()).unwrap_or(false)
 }
 
-fn for_all_targets<F: FnMut(String)>(sysroot: &Path, mut f: F) {
+fn target_has_std<P: Into<PathBuf>>(path: P) -> bool {
+    let mut path = path.into();
+    path.push("lib");
+    std::fs::read_dir(path)
+        .expect("invalid target")
+        .map(|entry| entry.unwrap())
+        .filter(|entry| entry.file_type().unwrap().is_file())
+        .filter_map(|entry| entry.file_name().into_string().ok())
+        .any(|file_name| file_name.starts_with("libstd") && file_name.ends_with(".rlib"))
+}
+
+
+fn for_all_targets<F: FnMut(String)>(sysroot: &Path, f: F) {
     let target_dir = sysroot.join("lib").join("rustlib");
-    for entry in std::fs::read_dir(target_dir).expect("invalid sysroot") {
-        let entry = entry.unwrap();
-        if !is_target_dir(entry.path()) {
-            continue;
-        }
-        let target = entry.file_name().into_string().unwrap();
-        f(target);
+    let mut targets = std::fs::read_dir(target_dir)
+        .expect("invalid sysroot")
+        .map(|entry| entry.unwrap())
+        .filter(|entry| is_target_dir(entry.path()))
+        .filter(|entry| target_has_std(entry.path()))
+        .map(|entry| entry.file_name().into_string().unwrap())
+        .peekable();
+
+    if targets.peek().is_none() {
+        panic!("No valid targets found");
     }
+
+    targets.for_each(f);
 }
 
 fn get_sysroot() -> PathBuf {