diff --git a/src/libstd/hash.rs b/src/libstd/hash.rs
index 16d138d4e1fb..5d4b9b4e3f0b 100644
--- a/src/libstd/hash.rs
+++ b/src/libstd/hash.rs
@@ -85,9 +85,10 @@ impl<A:IterBytes> Hash for A {
     #[inline]
     fn hash_keyed(&self, k0: u64, k1: u64) -> u64 {
         let mut s = State::new(k0, k1);
-        for self.iter_bytes(true) |bytes| {
+        do self.iter_bytes(true) |bytes| {
             s.input(bytes);
-        }
+            true
+        };
         s.result_u64()
     }
 }
@@ -95,12 +96,14 @@ impl<A:IterBytes> Hash for A {
 fn hash_keyed_2<A: IterBytes,
                 B: IterBytes>(a: &A, b: &B, k0: u64, k1: u64) -> u64 {
     let mut s = State::new(k0, k1);
-    for a.iter_bytes(true) |bytes| {
+    do a.iter_bytes(true) |bytes| {
         s.input(bytes);
-    }
-    for b.iter_bytes(true) |bytes| {
+        true
+    };
+    do b.iter_bytes(true) |bytes| {
         s.input(bytes);
-    }
+        true
+    };
     s.result_u64()
 }
 
@@ -108,15 +111,18 @@ fn hash_keyed_3<A: IterBytes,
                 B: IterBytes,
                 C: IterBytes>(a: &A, b: &B, c: &C, k0: u64, k1: u64) -> u64 {
     let mut s = State::new(k0, k1);
-    for a.iter_bytes(true) |bytes| {
+    do a.iter_bytes(true) |bytes| {
         s.input(bytes);
-    }
-    for b.iter_bytes(true) |bytes| {
+        true
+    };
+    do b.iter_bytes(true) |bytes| {
         s.input(bytes);
-    }
-    for c.iter_bytes(true) |bytes| {
+        true
+    };
+    do c.iter_bytes(true) |bytes| {
         s.input(bytes);
-    }
+        true
+    };
     s.result_u64()
 }
 
@@ -132,18 +138,22 @@ fn hash_keyed_4<A: IterBytes,
                 k1: u64)
                 -> u64 {
     let mut s = State::new(k0, k1);
-    for a.iter_bytes(true) |bytes| {
+    do a.iter_bytes(true) |bytes| {
         s.input(bytes);
-    }
-    for b.iter_bytes(true) |bytes| {
+        true
+    };
+    do b.iter_bytes(true) |bytes| {
         s.input(bytes);
-    }
-    for c.iter_bytes(true) |bytes| {
+        true
+    };
+    do c.iter_bytes(true) |bytes| {
         s.input(bytes);
-    }
-    for d.iter_bytes(true) |bytes| {
+        true
+    };
+    do d.iter_bytes(true) |bytes| {
         s.input(bytes);
-    }
+        true
+    };
     s.result_u64()
 }
 
@@ -161,21 +171,26 @@ fn hash_keyed_5<A: IterBytes,
                 k1: u64)
                 -> u64 {
     let mut s = State::new(k0, k1);
-    for a.iter_bytes(true) |bytes| {
+    do a.iter_bytes(true) |bytes| {
         s.input(bytes);
-    }
-    for b.iter_bytes(true) |bytes| {
+        true
+    };
+    do b.iter_bytes(true) |bytes| {
         s.input(bytes);
-    }
-    for c.iter_bytes(true) |bytes| {
+        true
+    };
+    do c.iter_bytes(true) |bytes| {
         s.input(bytes);
-    }
-    for d.iter_bytes(true) |bytes| {
+        true
+    };
+    do d.iter_bytes(true) |bytes| {
         s.input(bytes);
-    }
-    for e.iter_bytes(true) |bytes| {
+        true
+    };
+    do e.iter_bytes(true) |bytes| {
         s.input(bytes);
-    }
+        true
+    };
     s.result_u64()
 }
 
diff --git a/src/libstd/to_bytes.rs b/src/libstd/to_bytes.rs
index 60df31fd4ca8..5ad7969c8d21 100644
--- a/src/libstd/to_bytes.rs
+++ b/src/libstd/to_bytes.rs
@@ -353,9 +353,10 @@ pub trait ToBytes {
 impl<A:IterBytes> ToBytes for A {
     fn to_bytes(&self, lsb0: bool) -> ~[u8] {
         do io::with_bytes_writer |wr| {
-            for self.iter_bytes(lsb0) |bytes| {
-                wr.write(bytes)
-            }
+            do self.iter_bytes(lsb0) |bytes| {
+                wr.write(bytes);
+                true
+            };
         }
     }
 }