diff --git a/src/libcore/lib.rs b/src/libcore/lib.rs
index e8803976937d2..1e6d5bfad56aa 100644
--- a/src/libcore/lib.rs
+++ b/src/libcore/lib.rs
@@ -140,6 +140,7 @@ pub mod iter;
 pub mod option;
 pub mod raw;
 pub mod result;
+pub mod time;
 
 pub mod slice;
 pub mod str;
diff --git a/src/libstd/time/duration.rs b/src/libcore/time.rs
similarity index 69%
rename from src/libstd/time/duration.rs
rename to src/libcore/time.rs
index f1bbaa5e2ea8b..0e06040d7af04 100644
--- a/src/libstd/time/duration.rs
+++ b/src/libcore/time.rs
@@ -8,6 +8,10 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+//! Temporal quantification.
+
+#![stable(feature = "time", since = "1.3.0")]
+
 use ops::{Add, Sub, Mul, Div};
 
 const NANOS_PER_SEC: u32 = 1_000_000_000;
@@ -154,81 +158,3 @@ impl Div<u32> for Duration {
         Duration { secs: secs, nanos: nanos }
     }
 }
-
-#[cfg(test)]
-mod tests {
-    use super::Duration;
-
-    #[test]
-    fn creation() {
-        assert!(Duration::from_secs(1) != Duration::from_secs(0));
-        assert_eq!(Duration::from_secs(1) + Duration::from_secs(2),
-                   Duration::from_secs(3));
-        assert_eq!(Duration::from_millis(10) + Duration::from_secs(4),
-                   Duration::new(4, 10 * 1_000_000));
-        assert_eq!(Duration::from_millis(4000), Duration::new(4, 0));
-    }
-
-    #[test]
-    fn secs() {
-        assert_eq!(Duration::new(0, 0).as_secs(), 0);
-        assert_eq!(Duration::from_secs(1).as_secs(), 1);
-        assert_eq!(Duration::from_millis(999).as_secs(), 0);
-        assert_eq!(Duration::from_millis(1001).as_secs(), 1);
-    }
-
-    #[test]
-    fn nanos() {
-        assert_eq!(Duration::new(0, 0).subsec_nanos(), 0);
-        assert_eq!(Duration::new(0, 5).subsec_nanos(), 5);
-        assert_eq!(Duration::new(0, 1_000_000_001).subsec_nanos(), 1);
-        assert_eq!(Duration::from_secs(1).subsec_nanos(), 0);
-        assert_eq!(Duration::from_millis(999).subsec_nanos(), 999 * 1_000_000);
-        assert_eq!(Duration::from_millis(1001).subsec_nanos(), 1 * 1_000_000);
-    }
-
-    #[test]
-    fn add() {
-        assert_eq!(Duration::new(0, 0) + Duration::new(0, 1),
-                   Duration::new(0, 1));
-        assert_eq!(Duration::new(0, 500_000_000) + Duration::new(0, 500_000_001),
-                   Duration::new(1, 1));
-    }
-
-    #[test]
-    fn sub() {
-        assert_eq!(Duration::new(0, 1) - Duration::new(0, 0),
-                   Duration::new(0, 1));
-        assert_eq!(Duration::new(0, 500_000_001) - Duration::new(0, 500_000_000),
-                   Duration::new(0, 1));
-        assert_eq!(Duration::new(1, 0) - Duration::new(0, 1),
-                   Duration::new(0, 999_999_999));
-    }
-
-    #[test] #[should_panic]
-    fn sub_bad1() {
-        Duration::new(0, 0) - Duration::new(0, 1);
-    }
-
-    #[test] #[should_panic]
-    fn sub_bad2() {
-        Duration::new(0, 0) - Duration::new(1, 0);
-    }
-
-    #[test]
-    fn mul() {
-        assert_eq!(Duration::new(0, 1) * 2, Duration::new(0, 2));
-        assert_eq!(Duration::new(1, 1) * 3, Duration::new(3, 3));
-        assert_eq!(Duration::new(0, 500_000_001) * 4, Duration::new(2, 4));
-        assert_eq!(Duration::new(0, 500_000_001) * 4000,
-                   Duration::new(2000, 4000));
-    }
-
-    #[test]
-    fn div() {
-        assert_eq!(Duration::new(0, 1) / 2, Duration::new(0, 0));
-        assert_eq!(Duration::new(1, 1) / 3, Duration::new(0, 333_333_333));
-        assert_eq!(Duration::new(99, 999_999_000) / 100,
-                   Duration::new(0, 999_999_990));
-    }
-}
diff --git a/src/libcoretest/lib.rs b/src/libcoretest/lib.rs
index 88f1835d2cce4..a3b8887c0dbe7 100644
--- a/src/libcoretest/lib.rs
+++ b/src/libcoretest/lib.rs
@@ -71,4 +71,5 @@ mod ptr;
 mod result;
 mod slice;
 mod str;
+mod time;
 mod tuple;
diff --git a/src/libcoretest/time.rs b/src/libcoretest/time.rs
new file mode 100644
index 0000000000000..422227d74324f
--- /dev/null
+++ b/src/libcoretest/time.rs
@@ -0,0 +1,84 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use core::time::Duration;
+
+#[test]
+fn creation() {
+    assert!(Duration::from_secs(1) != Duration::from_secs(0));
+    assert_eq!(Duration::from_secs(1) + Duration::from_secs(2),
+               Duration::from_secs(3));
+    assert_eq!(Duration::from_millis(10) + Duration::from_secs(4),
+               Duration::new(4, 10 * 1_000_000));
+    assert_eq!(Duration::from_millis(4000), Duration::new(4, 0));
+}
+
+#[test]
+fn secs() {
+    assert_eq!(Duration::new(0, 0).as_secs(), 0);
+    assert_eq!(Duration::from_secs(1).as_secs(), 1);
+    assert_eq!(Duration::from_millis(999).as_secs(), 0);
+    assert_eq!(Duration::from_millis(1001).as_secs(), 1);
+}
+
+#[test]
+fn nanos() {
+    assert_eq!(Duration::new(0, 0).subsec_nanos(), 0);
+    assert_eq!(Duration::new(0, 5).subsec_nanos(), 5);
+    assert_eq!(Duration::new(0, 1_000_000_001).subsec_nanos(), 1);
+    assert_eq!(Duration::from_secs(1).subsec_nanos(), 0);
+    assert_eq!(Duration::from_millis(999).subsec_nanos(), 999 * 1_000_000);
+    assert_eq!(Duration::from_millis(1001).subsec_nanos(), 1 * 1_000_000);
+}
+
+#[test]
+fn add() {
+    assert_eq!(Duration::new(0, 0) + Duration::new(0, 1),
+               Duration::new(0, 1));
+    assert_eq!(Duration::new(0, 500_000_000) + Duration::new(0, 500_000_001),
+               Duration::new(1, 1));
+}
+
+#[test]
+fn sub() {
+    assert_eq!(Duration::new(0, 1) - Duration::new(0, 0),
+               Duration::new(0, 1));
+    assert_eq!(Duration::new(0, 500_000_001) - Duration::new(0, 500_000_000),
+               Duration::new(0, 1));
+    assert_eq!(Duration::new(1, 0) - Duration::new(0, 1),
+               Duration::new(0, 999_999_999));
+}
+
+#[test] #[should_panic]
+fn sub_bad1() {
+    Duration::new(0, 0) - Duration::new(0, 1);
+}
+
+#[test] #[should_panic]
+fn sub_bad2() {
+    Duration::new(0, 0) - Duration::new(1, 0);
+}
+
+#[test]
+fn mul() {
+    assert_eq!(Duration::new(0, 1) * 2, Duration::new(0, 2));
+    assert_eq!(Duration::new(1, 1) * 3, Duration::new(3, 3));
+    assert_eq!(Duration::new(0, 500_000_001) * 4, Duration::new(2, 4));
+    assert_eq!(Duration::new(0, 500_000_001) * 4000,
+               Duration::new(2000, 4000));
+}
+
+#[test]
+fn div() {
+    assert_eq!(Duration::new(0, 1) / 2, Duration::new(0, 0));
+    assert_eq!(Duration::new(1, 1) / 3, Duration::new(0, 333_333_333));
+    assert_eq!(Duration::new(99, 999_999_000) / 100,
+               Duration::new(0, 999_999_990));
+}
diff --git a/src/libstd/time/mod.rs b/src/libstd/time/mod.rs
index e3ce8e0de4b12..9aaaf1bbd6249 100644
--- a/src/libstd/time/mod.rs
+++ b/src/libstd/time/mod.rs
@@ -18,9 +18,7 @@ use ops::{Add, Sub};
 use sys::time;
 
 #[stable(feature = "time", since = "1.3.0")]
-pub use self::duration::Duration;
-
-mod duration;
+pub use core::time::Duration;
 
 /// A measurement of a monotonically increasing clock.
 ///