diff --git a/src/liballoc/boxed.rs b/src/liballoc/boxed.rs
index 7bdf9eaccc323..ef1c68bb6c7b6 100644
--- a/src/liballoc/boxed.rs
+++ b/src/liballoc/boxed.rs
@@ -68,6 +68,7 @@ use core::ops::{Placer, Boxed, Place, InPlace, BoxPlace};
 use core::ptr::{self, Unique};
 use core::raw::TraitObject;
 use core::convert::From;
+use core::error::Error;
 
 /// A value that represents the heap. This is the default place that the `box`
 /// keyword allocates into when no place is supplied.
@@ -641,3 +642,112 @@ impl<T: ?Sized> AsMut<T> for Box<T> {
         &mut **self
     }
 }
+
+
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<'a, E: Error + 'a> From<E> for Box<Error + 'a> {
+    fn from(err: E) -> Box<Error + 'a> {
+        Box::new(err)
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<'a, E: Error + Send + Sync + 'a> From<E> for Box<Error + Send + Sync + 'a> {
+    fn from(err: E) -> Box<Error + Send + Sync + 'a> {
+        Box::new(err)
+    }
+}
+
+impl Box<str> {
+    fn new_box_str(s: &str) -> Box<str> {
+        let len = s.len();
+        let buf = RawVec::with_capacity(len);
+        unsafe {
+            ptr::copy_nonoverlapping(s.as_ptr(), buf.ptr(), len);
+            mem::transmute(buf.into_box()) // bytes to str ~magic
+        }
+    }
+}
+
+#[unstable(feature="error_box_str",issue="0")]
+impl Error for Box<str> {
+    fn description(&self) -> &str {
+        self
+    }
+}
+
+impl Box<Error> {
+    #[inline]
+    #[stable(feature = "error_downcast", since = "1.3.0")]
+    /// Attempt to downcast the box to a concrete type.
+    pub fn downcast<T: Error + 'static>(self) -> Result<Box<T>, Box<Error>> {
+        if self.is::<T>() {
+            unsafe {
+                // Get the raw representation of the trait object
+                let raw = Box::into_raw(self);
+                let to: TraitObject =
+                    mem::transmute::<*mut Error, TraitObject>(raw);
+
+                // Extract the data pointer
+                Ok(Box::from_raw(to.data as *mut T))
+            }
+        } else {
+            Err(self)
+        }
+    }
+}
+
+impl Box<Error + Send> {
+    #[inline]
+    #[stable(feature = "error_downcast", since = "1.3.0")]
+    /// Attempt to downcast the box to a concrete type.
+    pub fn downcast<T: Error + 'static>(self)
+                                        -> Result<Box<T>, Box<Error + Send>> {
+        let err: Box<Error> = self;
+        <Box<Error>>::downcast(err).map_err(|s| unsafe {
+            // reapply the Send marker
+            mem::transmute::<Box<Error>, Box<Error + Send>>(s)
+        })
+    }
+}
+
+impl Box<Error + Send + Sync> {
+    #[inline]
+    #[stable(feature = "error_downcast", since = "1.3.0")]
+    /// Attempt to downcast the box to a concrete type.
+    pub fn downcast<T: Error + 'static>(self)
+                                        -> Result<Box<T>, Self> {
+        let err: Box<Error> = self;
+        <Box<Error>>::downcast(err).map_err(|s| unsafe {
+            // reapply the Send+Sync marker
+            mem::transmute::<Box<Error>, Box<Error + Send + Sync>>(s)
+        })
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<'a, 'b> From<&'b str> for Box<Error + Send + Sync + 'a> {
+    fn from(err: &'b str) -> Box<Error + Send + Sync + 'a> {
+        From::from(Box::new_box_str(err))
+    }
+}
+
+#[stable(feature = "string_box_error", since = "1.7.0")]
+impl<'a> From<&'a str> for Box<Error> {
+    fn from(err: &'a str) -> Box<Error> {
+        From::from(Box::new_box_str(err))
+    }
+}
+
+#[stable(feature = "box_error", since = "1.7.0")]
+impl<T: Error> Error for Box<T> {
+    fn description(&self) -> &str {
+        Error::description(&**self)
+    }
+
+    fn cause(&self) -> Option<&Error> {
+        Error::cause(&**self)
+    }
+}
+
diff --git a/src/libcollections/string.rs b/src/libcollections/string.rs
index 306fad2328b62..5d99898ae2be0 100644
--- a/src/libcollections/string.rs
+++ b/src/libcollections/string.rs
@@ -62,6 +62,7 @@ use core::mem;
 use core::ops::{self, Add, Index, IndexMut};
 use core::ptr;
 use core::str::pattern::Pattern;
+use core::error::Error;
 use rustc_unicode::char::{decode_utf16, REPLACEMENT_CHARACTER};
 use rustc_unicode::str as unicode_str;
 
@@ -1897,3 +1898,56 @@ impl<'a> DoubleEndedIterator for Drain<'a> {
         self.iter.next_back()
     }
 }
+
+
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl From<String> for Box<Error + Send + Sync> {
+    fn from(err: String) -> Box<Error + Send + Sync> {
+        #[derive(Debug)]
+        struct StringError(String);
+
+        impl Error for StringError {
+            fn description(&self) -> &str { &self.0 }
+        }
+
+        impl fmt::Display for StringError {
+            fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+                fmt::Display::fmt(&self.0, f)
+            }
+        }
+
+        Box::new(StringError(err))
+    }
+}
+
+#[stable(feature = "string_box_error", since = "1.7.0")]
+impl From<String> for Box<Error> {
+    fn from(str_err: String) -> Box<Error> {
+        let err1: Box<Error + Send + Sync> = From::from(str_err);
+        let err2: Box<Error> = err1;
+        err2
+    }
+}
+
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl Error for FromUtf8Error {
+    fn description(&self) -> &str {
+        "invalid utf-8"
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl Error for FromUtf16Error {
+    fn description(&self) -> &str {
+        "invalid utf-16"
+    }
+}
+
+#[stable(feature = "str_parse_error2", since = "1.8.0")]
+impl Error for ParseError {
+    fn description(&self) -> &str {
+        match *self {}
+    }
+}
diff --git a/src/libstd/error.rs b/src/libcore/error.rs
similarity index 65%
rename from src/libstd/error.rs
rename to src/libcore/error.rs
index 35cd4a5ec5292..31c6192d3cdfa 100644
--- a/src/libstd/error.rs
+++ b/src/libcore/error.rs
@@ -48,18 +48,17 @@
 // reconsider what crate these items belong in.
 
 use any::TypeId;
-use boxed::Box;
-use char;
-use fmt::{self, Debug, Display};
+use fmt::{Debug, Display};
 use marker::{Send, Sync, Reflect};
 use mem::transmute;
 use num;
 use raw::TraitObject;
 use str;
-use string::{self, String};
+use option::Option::{self, Some, None};
 
 /// Base functionality for all errors in Rust.
 #[stable(feature = "rust1", since = "1.0.0")]
+#[fundamental]
 pub trait Error: Debug + Display + Reflect {
     /// A short description of the error.
     ///
@@ -83,63 +82,6 @@ pub trait Error: Debug + Display + Reflect {
     }
 }
 
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, E: Error + 'a> From<E> for Box<Error + 'a> {
-    fn from(err: E) -> Box<Error + 'a> {
-        Box::new(err)
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, E: Error + Send + Sync + 'a> From<E> for Box<Error + Send + Sync + 'a> {
-    fn from(err: E) -> Box<Error + Send + Sync + 'a> {
-        Box::new(err)
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl From<String> for Box<Error + Send + Sync> {
-    fn from(err: String) -> Box<Error + Send + Sync> {
-        #[derive(Debug)]
-        struct StringError(String);
-
-        impl Error for StringError {
-            fn description(&self) -> &str { &self.0 }
-        }
-
-        impl Display for StringError {
-            fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-                Display::fmt(&self.0, f)
-            }
-        }
-
-        Box::new(StringError(err))
-    }
-}
-
-#[stable(feature = "string_box_error", since = "1.7.0")]
-impl From<String> for Box<Error> {
-    fn from(str_err: String) -> Box<Error> {
-        let err1: Box<Error + Send + Sync> = From::from(str_err);
-        let err2: Box<Error> = err1;
-        err2
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, 'b> From<&'b str> for Box<Error + Send + Sync + 'a> {
-    fn from(err: &'b str) -> Box<Error + Send + Sync + 'a> {
-        From::from(String::from(err))
-    }
-}
-
-#[stable(feature = "string_box_error", since = "1.7.0")]
-impl<'a> From<&'a str> for Box<Error> {
-    fn from(err: &'a str) -> Box<Error> {
-        From::from(String::from(err))
-    }
-}
-
 #[stable(feature = "rust1", since = "1.0.0")]
 impl Error for str::ParseBoolError {
     fn description(&self) -> &str { "failed to parse bool" }
@@ -166,45 +108,6 @@ impl Error for num::ParseFloatError {
     }
 }
 
-#[stable(feature = "rust1", since = "1.0.0")]
-impl Error for string::FromUtf8Error {
-    fn description(&self) -> &str {
-        "invalid utf-8"
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl Error for string::FromUtf16Error {
-    fn description(&self) -> &str {
-        "invalid utf-16"
-    }
-}
-
-#[stable(feature = "str_parse_error2", since = "1.8.0")]
-impl Error for string::ParseError {
-    fn description(&self) -> &str {
-        match *self {}
-    }
-}
-
-#[stable(feature = "decode_utf16", since = "1.9.0")]
-impl Error for char::DecodeUtf16Error {
-    fn description(&self) -> &str {
-        "unpaired surrogate found"
-    }
-}
-
-#[stable(feature = "box_error", since = "1.7.0")]
-impl<T: Error> Error for Box<T> {
-    fn description(&self) -> &str {
-        Error::description(&**self)
-    }
-
-    fn cause(&self) -> Option<&Error> {
-        Error::cause(&**self)
-    }
-}
-
 // copied from any.rs
 impl Error + 'static {
     /// Returns true if the boxed type is the same as `T`
@@ -304,55 +207,6 @@ impl Error + 'static + Send + Sync {
     }
 }
 
-impl Error {
-    #[inline]
-    #[stable(feature = "error_downcast", since = "1.3.0")]
-    /// Attempt to downcast the box to a concrete type.
-    pub fn downcast<T: Error + 'static>(self: Box<Self>) -> Result<Box<T>, Box<Error>> {
-        if self.is::<T>() {
-            unsafe {
-                // Get the raw representation of the trait object
-                let raw = Box::into_raw(self);
-                let to: TraitObject =
-                    transmute::<*mut Error, TraitObject>(raw);
-
-                // Extract the data pointer
-                Ok(Box::from_raw(to.data as *mut T))
-            }
-        } else {
-            Err(self)
-        }
-    }
-}
-
-impl Error + Send {
-    #[inline]
-    #[stable(feature = "error_downcast", since = "1.3.0")]
-    /// Attempt to downcast the box to a concrete type.
-    pub fn downcast<T: Error + 'static>(self: Box<Self>)
-                                        -> Result<Box<T>, Box<Error + Send>> {
-        let err: Box<Error> = self;
-        <Error>::downcast(err).map_err(|s| unsafe {
-            // reapply the Send marker
-            transmute::<Box<Error>, Box<Error + Send>>(s)
-        })
-    }
-}
-
-impl Error + Send + Sync {
-    #[inline]
-    #[stable(feature = "error_downcast", since = "1.3.0")]
-    /// Attempt to downcast the box to a concrete type.
-    pub fn downcast<T: Error + 'static>(self: Box<Self>)
-                                        -> Result<Box<T>, Box<Self>> {
-        let err: Box<Error> = self;
-        <Error>::downcast(err).map_err(|s| unsafe {
-            // reapply the Send+Sync marker
-            transmute::<Box<Error>, Box<Error + Send + Sync>>(s)
-        })
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use prelude::v1::*;
diff --git a/src/libcore/lib.rs b/src/libcore/lib.rs
index fa5e90562d80e..8a20eb4ec81e6 100644
--- a/src/libcore/lib.rs
+++ b/src/libcore/lib.rs
@@ -152,5 +152,7 @@ pub mod str;
 pub mod hash;
 pub mod fmt;
 
+pub mod error;
+
 // note: does not need to be public
 mod tuple;
diff --git a/src/librustc_unicode/char.rs b/src/librustc_unicode/char.rs
index 863cada5b8809..b1d70240f9df2 100644
--- a/src/librustc_unicode/char.rs
+++ b/src/librustc_unicode/char.rs
@@ -754,6 +754,13 @@ pub struct DecodeUtf16Error {
     code: u16,
 }
 
+#[stable(feature = "decode_utf16", since = "1.9.0")]
+impl ::core::error::Error for DecodeUtf16Error {
+    fn description(&self) -> &str {
+        "unpaired surrogate found"
+    }
+}
+
 /// Create an iterator over the UTF-16 encoded code points in `iter`,
 /// returning unpaired surrogates as `Err`s.
 ///
diff --git a/src/libstd/io/error.rs b/src/libstd/io/error.rs
index 9a605fc7bbff4..1261baceac716 100644
--- a/src/libstd/io/error.rs
+++ b/src/libstd/io/error.rs
@@ -10,7 +10,7 @@
 
 use boxed::Box;
 use convert::Into;
-use error;
+use core::error;
 use fmt;
 use marker::{Send, Sync};
 use option::Option::{self, Some, None};
diff --git a/src/libstd/lib.rs b/src/libstd/lib.rs
index e14a31453d381..f2833157340ab 100644
--- a/src/libstd/lib.rs
+++ b/src/libstd/lib.rs
@@ -341,13 +341,14 @@ pub use core::result;
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::option;
 
-pub mod error;
-
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use alloc::boxed;
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use alloc::rc;
 
+#[stable(feature = "rust1", since = "1.0.0")]
+pub use core::error;
+
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core_collections::borrow;
 #[stable(feature = "rust1", since = "1.0.0")]