diff --git a/src/libstd/fmt/mod.rs b/src/libstd/fmt/mod.rs
index 3223ca9a731..e7fa81fc87a 100644
--- a/src/libstd/fmt/mod.rs
+++ b/src/libstd/fmt/mod.rs
@@ -466,7 +466,7 @@ use rt::io::Decorator;
 use rt::io::mem::MemWriter;
 use rt::io;
 use str;
-use sys;
+use repr;
 use util;
 use vec;
 
@@ -1087,17 +1087,13 @@ impl<T> Poly for T {
     fn fmt(t: &T, f: &mut Formatter) {
         match (f.width, f.precision) {
             (None, None) => {
-                // XXX: sys::log_str should have a variant which takes a stream
-                //      and we should directly call that (avoids unnecessary
-                //      allocations)
-                let s = sys::log_str(t);
-                f.buf.write(s.as_bytes());
+                repr::write_repr(f.buf, t);
             }
 
             // If we have a specified width for formatting, then we have to make
             // this allocation of a new string
             _ => {
-                let s = sys::log_str(t);
+                let s = repr::repr_to_str(t);
                 f.pad(s);
             }
         }
diff --git a/src/libstd/repr.rs b/src/libstd/repr.rs
index 031fd7993eb..a788064293f 100644
--- a/src/libstd/repr.rs
+++ b/src/libstd/repr.rs
@@ -616,6 +616,16 @@ pub fn write_repr<T>(writer: &mut io::Writer, object: &T) {
     }
 }
 
+pub fn repr_to_str<T>(t: &T) -> ~str {
+    use str;
+    use rt::io;
+    use rt::io::Decorator;
+
+    let mut result = io::mem::MemWriter::new();
+    write_repr(&mut result as &mut io::Writer, t);
+    str::from_utf8_owned(result.inner())
+}
+
 #[cfg(test)]
 struct P {a: int, b: f64}
 
diff --git a/src/libstd/sys.rs b/src/libstd/sys.rs
index 0f38671bfc2..d20a6696e27 100644
--- a/src/libstd/sys.rs
+++ b/src/libstd/sys.rs
@@ -15,18 +15,7 @@
 use c_str::ToCStr;
 use libc::size_t;
 use libc;
-use repr;
 use rt::task;
-use str;
-
-pub fn log_str<T>(t: &T) -> ~str {
-    use rt::io;
-    use rt::io::Decorator;
-
-    let mut result = io::mem::MemWriter::new();
-    repr::write_repr(&mut result as &mut io::Writer, t);
-    str::from_utf8_owned(result.inner())
-}
 
 /// Trait for initiating task failure.
 pub trait FailWithCause {
diff --git a/src/libsyntax/ext/deriving/to_str.rs b/src/libsyntax/ext/deriving/to_str.rs
index fa13f78d0f9..77dbafa5ad7 100644
--- a/src/libsyntax/ext/deriving/to_str.rs
+++ b/src/libsyntax/ext/deriving/to_str.rs
@@ -40,9 +40,10 @@ pub fn expand_deriving_to_str(cx: @ExtCtxt,
 }
 
 // It used to be the case that this deriving implementation invoked
-// std::sys::log_str, but this isn't sufficient because it doesn't invoke the
-// to_str() method on each field. Hence we mirror the logic of the log_str()
-// method, but with tweaks to call to_str() on sub-fields.
+// std::repr::repr_to_str, but this isn't sufficient because it
+// doesn't invoke the to_str() method on each field. Hence we mirror
+// the logic of the repr_to_str() method, but with tweaks to call to_str()
+// on sub-fields.
 fn to_str_substructure(cx: @ExtCtxt, span: Span,
                        substr: &Substructure) -> @Expr {
     let to_str = cx.ident_of("to_str");
diff --git a/src/test/run-pass/fixed_length_vec_glue.rs b/src/test/run-pass/fixed_length_vec_glue.rs
index ab34245a8f0..d778844f4d7 100644
--- a/src/test/run-pass/fixed_length_vec_glue.rs
+++ b/src/test/run-pass/fixed_length_vec_glue.rs
@@ -10,13 +10,13 @@
 
 // xfail-fast: check-fast screws up repr paths
 
-use std::sys;
+use std::repr;
 
 struct Struc { a: u8, b: [int, ..3], c: int }
 
 pub fn main() {
     let arr = [1,2,3];
     let struc = Struc {a: 13u8, b: arr, c: 42};
-    let s = sys::log_str(&struc);
+    let s = repr::repr_to_str(&struc);
     assert_eq!(s, ~"Struc{a: 13u8, b: [1, 2, 3], c: 42}");
 }
diff --git a/src/test/run-pass/log-str.rs b/src/test/run-pass/log-str.rs
index a8914de917e..8859b533626 100644
--- a/src/test/run-pass/log-str.rs
+++ b/src/test/run-pass/log-str.rs
@@ -8,10 +8,10 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use std::sys;
+use std::repr;
 
 pub fn main() {
-    let act = sys::log_str(&~[1, 2, 3]);
+    let act = repr::repr_to_str(&~[1, 2, 3]);
     assert_eq!(~"~[1, 2, 3]", act);
 
     let act = format!("{:?}/{:6?}", ~[1, 2, 3], ~"hi");