diff --git a/src/librand/chacha.rs b/src/librand/chacha.rs
index 6fc92e1e94fcb..525f7e44f34c3 100644
--- a/src/librand/chacha.rs
+++ b/src/librand/chacha.rs
@@ -29,7 +29,7 @@ const CHACHA_ROUNDS: uint = 20; // Cryptographically secure from 8 upwards as of
 /// [1]: D. J. Bernstein, [*ChaCha, a variant of
 /// Salsa20*](http://cr.yp.to/chacha.html)
 
-#[deriving(Copy)]
+#[allow(missing_copy_implementations)]
 pub struct ChaChaRng {
     buffer:  [u32, ..STATE_WORDS], // Internal buffer of output
     state:   [u32, ..STATE_WORDS], // Initial state
@@ -85,7 +85,7 @@ impl ChaChaRng {
     /// Create an ChaCha random number generator using the default
     /// fixed key of 8 zero words.
     pub fn new_unseeded() -> ChaChaRng {
-        let mut rng = EMPTY;
+        let mut rng = EMPTY.clone();
         rng.init(&[0, ..KEY_WORDS]);
         rng
     }
@@ -157,6 +157,16 @@ impl ChaChaRng {
     }
 }
 
+impl Clone for ChaChaRng {
+    fn clone(&self) -> ChaChaRng {
+        ChaChaRng {
+            buffer:  self.buffer,
+            state:   self.state,
+            index:   self.index
+        }
+    }
+}
+
 impl Rng for ChaChaRng {
     #[inline]
     fn next_u32(&mut self) -> u32 {
@@ -187,7 +197,7 @@ impl<'a> SeedableRng<&'a [u32]> for ChaChaRng {
     /// Only up to 8 words are used; if less than 8
     /// words are used, the remaining are set to zero.
     fn from_seed(seed: &'a [u32]) -> ChaChaRng {
-        let mut rng = EMPTY;
+        let mut rng = EMPTY.clone();
         rng.reseed(seed);
         rng
     }
@@ -203,7 +213,6 @@ impl Rand for ChaChaRng {
     }
 }
 
-
 #[cfg(test)]
 mod test {
     use std::prelude::*;
diff --git a/src/librand/isaac.rs b/src/librand/isaac.rs
index 3cb1f51a6a801..e6458ec8a3a31 100644
--- a/src/librand/isaac.rs
+++ b/src/librand/isaac.rs
@@ -29,7 +29,8 @@ const RAND_SIZE_UINT: uint = 1 << (RAND_SIZE_LEN as uint);
 ///
 /// [1]: Bob Jenkins, [*ISAAC: A fast cryptographic random number
 /// generator*](http://www.burtleburtle.net/bob/rand/isaacafa.html)
-#[deriving(Copy)]
+
+#[allow(missing_copy_implementations)]
 pub struct IsaacRng {
     cnt: u32,
     rsl: [u32, ..RAND_SIZE_UINT],
@@ -51,7 +52,7 @@ impl IsaacRng {
     /// Create an ISAAC random number generator using the default
     /// fixed seed.
     pub fn new_unseeded() -> IsaacRng {
-        let mut rng = EMPTY;
+        let mut rng = EMPTY.clone();
         rng.init(false);
         rng
     }
@@ -179,6 +180,19 @@ impl IsaacRng {
     }
 }
 
+impl Clone for IsaacRng {
+    fn clone(&self) -> IsaacRng {
+        IsaacRng {
+            cnt: self.cnt,
+            rsl: self.rsl,
+            mem: self.mem,
+            a: self.a,
+            b: self.b,
+            c: self.c
+        }
+    }
+}
+
 impl Rng for IsaacRng {
     #[inline]
     fn next_u32(&mut self) -> u32 {
@@ -226,7 +240,7 @@ impl<'a> SeedableRng<&'a [u32]> for IsaacRng {
     /// constructed with a given seed will generate the same sequence
     /// of values as all other generators constructed with that seed.
     fn from_seed(seed: &'a [u32]) -> IsaacRng {
-        let mut rng = EMPTY;
+        let mut rng = EMPTY.clone();
         rng.reseed(seed);
         rng
     }
@@ -234,7 +248,7 @@ impl<'a> SeedableRng<&'a [u32]> for IsaacRng {
 
 impl Rand for IsaacRng {
     fn rand<R: Rng>(other: &mut R) -> IsaacRng {
-        let mut ret = EMPTY;
+        let mut ret = EMPTY.clone();
         unsafe {
             let ptr = ret.rsl.as_mut_ptr() as *mut u8;
 
@@ -264,7 +278,7 @@ const RAND_SIZE_64: uint = 1 << RAND_SIZE_64_LEN;
 ///
 /// [1]: Bob Jenkins, [*ISAAC: A fast cryptographic random number
 /// generator*](http://www.burtleburtle.net/bob/rand/isaacafa.html)
-#[deriving(Copy)]
+#[allow(missing_copy_implementations)]
 pub struct Isaac64Rng {
     cnt: uint,
     rsl: [u64, .. RAND_SIZE_64],
@@ -285,7 +299,7 @@ impl Isaac64Rng {
     /// Create a 64-bit ISAAC random number generator using the
     /// default fixed seed.
     pub fn new_unseeded() -> Isaac64Rng {
-        let mut rng = EMPTY_64;
+        let mut rng = EMPTY_64.clone();
         rng.init(false);
         rng
     }
@@ -415,6 +429,19 @@ impl Isaac64Rng {
     }
 }
 
+impl Clone for Isaac64Rng {
+    fn clone(&self) -> Isaac64Rng {
+        Isaac64Rng {
+            cnt: self.cnt,
+            rsl: self.rsl,
+            mem: self.mem,
+            a: self.a,
+            b: self.b,
+            c: self.c
+        }
+    }
+}
+
 impl Rng for Isaac64Rng {
     // FIXME #7771: having next_u32 like this should be unnecessary
     #[inline]
@@ -460,7 +487,7 @@ impl<'a> SeedableRng<&'a [u64]> for Isaac64Rng {
     /// constructed with a given seed will generate the same sequence
     /// of values as all other generators constructed with that seed.
     fn from_seed(seed: &'a [u64]) -> Isaac64Rng {
-        let mut rng = EMPTY_64;
+        let mut rng = EMPTY_64.clone();
         rng.reseed(seed);
         rng
     }
@@ -468,7 +495,7 @@ impl<'a> SeedableRng<&'a [u64]> for Isaac64Rng {
 
 impl Rand for Isaac64Rng {
     fn rand<R: Rng>(other: &mut R) -> Isaac64Rng {
-        let mut ret = EMPTY_64;
+        let mut ret = EMPTY_64.clone();
         unsafe {
             let ptr = ret.rsl.as_mut_ptr() as *mut u8;
 
diff --git a/src/libstd/rand/mod.rs b/src/libstd/rand/mod.rs
index c590c0f575ee6..78645b20fba16 100644
--- a/src/libstd/rand/mod.rs
+++ b/src/libstd/rand/mod.rs
@@ -245,7 +245,8 @@ pub mod reader;
 
 /// The standard RNG. This is designed to be efficient on the current
 /// platform.
-#[deriving(Copy)]
+#[allow(missing_copy_implementations)]
+#[deriving(Clone)]
 pub struct StdRng {
     rng: IsaacWordRng,
 }