diff --git a/src/libstd/sys/unix/thread.rs b/src/libstd/sys/unix/thread.rs
index 793a2ecae89f1..6d966a0f6944c 100644
--- a/src/libstd/sys/unix/thread.rs
+++ b/src/libstd/sys/unix/thread.rs
@@ -13,7 +13,7 @@ use prelude::v1::*;
 use alloc::boxed::FnBox;
 use cmp;
 #[cfg(not(any(target_env = "newlib", target_os = "solaris")))]
-use ffi::CString;
+use ffi::CStr;
 use io;
 use libc;
 use mem;
@@ -84,15 +84,12 @@ impl Thread {
     #[cfg(any(target_os = "linux",
               target_os = "android",
               target_os = "emscripten"))]
-    pub fn set_name(name: &str) {
+    pub fn set_name(name: &CStr) {
         const PR_SET_NAME: libc::c_int = 15;
-        let cname = CString::new(name).unwrap_or_else(|_| {
-            panic!("thread name may not contain interior null bytes")
-        });
         // pthread wrapper only appeared in glibc 2.12, so we use syscall
         // directly.
         unsafe {
-            libc::prctl(PR_SET_NAME, cname.as_ptr() as libc::c_ulong, 0, 0, 0);
+            libc::prctl(PR_SET_NAME, name.as_ptr() as libc::c_ulong, 0, 0, 0);
         }
     }
 
@@ -100,32 +97,30 @@ impl Thread {
               target_os = "dragonfly",
               target_os = "bitrig",
               target_os = "openbsd"))]
-    pub fn set_name(name: &str) {
-        let cname = CString::new(name).unwrap();
+    pub fn set_name(name: &CStr) {
         unsafe {
-            libc::pthread_set_name_np(libc::pthread_self(), cname.as_ptr());
+            libc::pthread_set_name_np(libc::pthread_self(), name.as_ptr());
         }
     }
 
     #[cfg(any(target_os = "macos", target_os = "ios"))]
-    pub fn set_name(name: &str) {
-        let cname = CString::new(name).unwrap();
+    pub fn set_name(name: &CStr) {
         unsafe {
-            libc::pthread_setname_np(cname.as_ptr());
+            libc::pthread_setname_np(name.as_ptr());
         }
     }
 
     #[cfg(target_os = "netbsd")]
-    pub fn set_name(name: &str) {
+    pub fn set_name(name: &CStr) {
+        use ffi::CString;
         let cname = CString::new(&b"%s"[..]).unwrap();
-        let carg = CString::new(name).unwrap();
         unsafe {
             libc::pthread_setname_np(libc::pthread_self(), cname.as_ptr(),
-                                     carg.as_ptr() as *mut libc::c_void);
+                                     name.as_ptr() as *mut libc::c_void);
         }
     }
     #[cfg(any(target_env = "newlib", target_os = "solaris"))]
-    pub fn set_name(_name: &str) {
+    pub fn set_name(_name: &CStr) {
         // Newlib and Illumos has no way to set a thread name.
     }
 
diff --git a/src/libstd/sys/windows/thread.rs b/src/libstd/sys/windows/thread.rs
index b18772c0c2438..6908775e86fc1 100644
--- a/src/libstd/sys/windows/thread.rs
+++ b/src/libstd/sys/windows/thread.rs
@@ -54,7 +54,7 @@ impl Thread {
         }
     }
 
-    pub fn set_name(_name: &str) {
+    pub fn set_name(_name: &CStr) {
         // Windows threads are nameless
         // The names in MSVC debugger are obtained using a "magic" exception,
         // which requires a use of MS C++ extensions.
diff --git a/src/libstd/thread/mod.rs b/src/libstd/thread/mod.rs
index f3139aaf98d83..b3549dc12645a 100644
--- a/src/libstd/thread/mod.rs
+++ b/src/libstd/thread/mod.rs
@@ -166,6 +166,8 @@ use any::Any;
 use cell::UnsafeCell;
 use fmt;
 use io;
+use str;
+use ffi::{CStr, CString};
 use sync::{Mutex, Condvar, Arc};
 use sys::thread as imp;
 use sys_common::thread_info;
@@ -267,7 +269,7 @@ impl Builder {
         let their_packet = my_packet.clone();
 
         let main = move || {
-            if let Some(name) = their_thread.name() {
+            if let Some(name) = their_thread.cname() {
                 imp::Thread::set_name(name);
             }
             unsafe {
@@ -450,7 +452,7 @@ pub fn park_timeout(dur: Duration) {
 
 /// The internal representation of a `Thread` handle
 struct Inner {
-    name: Option<String>,
+    name: Option<CString>,      // Guaranteed to be UTF-8
     lock: Mutex<bool>,          // true when there is a buffered unpark
     cvar: Condvar,
 }
@@ -465,9 +467,12 @@ pub struct Thread {
 impl Thread {
     // Used only internally to construct a thread object without spawning
     fn new(name: Option<String>) -> Thread {
+        let cname = name.map(|n| CString::new(n).unwrap_or_else(|_| {
+            panic!("thread name may not contain interior null bytes")
+        }));
         Thread {
             inner: Arc::new(Inner {
-                name: name,
+                name: cname,
                 lock: Mutex::new(false),
                 cvar: Condvar::new(),
             })
@@ -489,6 +494,10 @@ impl Thread {
     /// Gets the thread's name.
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn name(&self) -> Option<&str> {
+        self.cname().map(|s| unsafe { str::from_utf8_unchecked(s.to_bytes()) } )
+    }
+
+    fn cname(&self) -> Option<&CStr> {
         self.inner.name.as_ref().map(|s| &**s)
     }
 }
@@ -622,6 +631,12 @@ mod tests {
         }).unwrap().join().unwrap();
     }
 
+    #[test]
+    #[should_panic]
+    fn test_invalid_named_thread() {
+        let _ = Builder::new().name("ada l\0velace".to_string()).spawn(|| {});
+    }
+
     #[test]
     fn test_run_basic() {
         let (tx, rx) = channel();