diff --git a/.travis.yml b/.travis.yml
index bbfd88c..d1722b5 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,6 +2,7 @@ language: rust
 sudo: false
 matrix:
   include:
+    - rust: 1.2.0
     - rust: stable
     - rust: beta
     - rust: nightly
diff --git a/src/array_string.rs b/src/array_string.rs
index 154b74c..a39fbcc 100644
--- a/src/array_string.rs
+++ b/src/array_string.rs
@@ -1,7 +1,8 @@
 use std::borrow::Borrow;
 use std::fmt;
 use std::hash::{Hash, Hasher};
-use std::ops::Deref;
+use std::mem;
+use std::ops::{Deref, DerefMut};
 use std::str;
 use std::slice;
 
@@ -99,7 +100,7 @@ impl<A: Array<Item=u8>> ArrayString<A> {
     pub fn push_str<'a>(&mut self, s: &'a str) -> Result<(), CapacityError<&'a str>> {
         use std::io::Write;
 
-        if self.len() + s.len() > self.capacity() {
+        if s.len() > self.capacity() - self.len() {
             return Err(CapacityError::new(s));
         }
         unsafe {
@@ -142,6 +143,17 @@ impl<A: Array<Item=u8>> Deref for ArrayString<A> {
     }
 }
 
+impl<A: Array<Item=u8>> DerefMut for ArrayString<A> {
+    #[inline]
+    fn deref_mut(&mut self) -> &mut str {
+        unsafe {
+            let sl = slice::from_raw_parts_mut(self.xs.as_mut_ptr(), self.len.to_usize());
+            // FIXME: Nothing but transmute to do this right now
+            mem::transmute(sl)
+        }
+    }
+}
+
 impl<A: Array<Item=u8>> PartialEq for ArrayString<A> {
     fn eq(&self, rhs: &Self) -> bool {
         **self == **rhs
diff --git a/src/lib.rs b/src/lib.rs
index ea20055..ad576c5 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -57,9 +57,7 @@ pub struct ArrayVec<A: Array> {
 
 impl<A: Array> Drop for ArrayVec<A> {
     fn drop(&mut self) {
-        // clear all elements
-        while let Some(_) = self.pop() {
-        }
+        self.clear();
 
         // NoDrop inhibits array's drop
         // panic safety: NoDrop::drop will trigger on panic, so the inner
@@ -340,6 +338,12 @@ impl<A: Array> ArrayVec<A> {
             }
         }
     }
+
+    /// Dispose of `self` without the overwriting that is needed in Drop.
+    pub fn dispose(mut self) {
+        self.clear();
+        mem::forget(self);
+    }
 }
 
 impl<A: Array> Deref for ArrayVec<A> {
@@ -701,7 +705,7 @@ impl<A: Array<Item=u8>> io::Write for ArrayVec<A> {
 
 /// Error value indicating insufficient capacity
 #[derive(Clone, Copy, Eq, Ord, PartialEq, PartialOrd)]
-pub struct CapacityError<T> {
+pub struct CapacityError<T = ()> {
     element: T,
 }
 
@@ -716,6 +720,11 @@ impl<T> CapacityError<T> {
     pub fn element(self) -> T {
         self.element
     }
+
+    /// Convert into a `CapacityError` that does not carry an element.
+    pub fn simplify(self) -> CapacityError {
+        CapacityError { element: () }
+    }
 }
 
 const CAPERROR: &'static str = "insufficient capacity";
diff --git a/tests/tests.rs b/tests/tests.rs
index 3dd24bd..b0b256d 100644
--- a/tests/tests.rs
+++ b/tests/tests.rs
@@ -283,6 +283,12 @@ fn test_string() {
     assert!(t.push_str(text).is_err());
     assert_eq!(&t, "");
 
+    t.push_str("ab").unwrap();
+    // DerefMut
+    let tmut: &mut str = &mut t;
+    assert_eq!(tmut, "ab");
+
+
     // Test Error trait / try
     let t = || -> Result<(), Box<Error>> {
         let mut t = ArrayString::<[_; 2]>::new();