diff --git a/src/libcollections/enum_set.rs b/src/libcollections/enum_set.rs
index 7e7e8ba2356..32cd4193d88 100644
--- a/src/libcollections/enum_set.rs
+++ b/src/libcollections/enum_set.rs
@@ -49,16 +49,7 @@ impl<E> Clone for EnumSet<E> {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<E:CLike + fmt::Debug> fmt::Debug for EnumSet<E> {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        try!(write!(fmt, "{{"));
-        let mut first = true;
-        for e in self {
-            if !first {
-                try!(write!(fmt, ", "));
-            }
-            try!(write!(fmt, "{:?}", e));
-            first = false;
-        }
-        write!(fmt, "}}")
+        fmt.debug_set().entries(self).finish()
     }
 }
 
diff --git a/src/libcollections/vec_deque.rs b/src/libcollections/vec_deque.rs
index 4ee9787c9ec..6de5f27068d 100644
--- a/src/libcollections/vec_deque.rs
+++ b/src/libcollections/vec_deque.rs
@@ -1787,14 +1787,7 @@ impl<'a, T: 'a + Copy> Extend<&'a T> for VecDeque<T> {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: fmt::Debug> fmt::Debug for VecDeque<T> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        try!(write!(f, "["));
-
-        for (i, e) in self.iter().enumerate() {
-            if i != 0 { try!(write!(f, ", ")); }
-            try!(write!(f, "{:?}", *e));
-        }
-
-        write!(f, "]")
+        f.debug_list().entries(self).finish()
     }
 }