diff --git a/src/lib.rs b/src/lib.rs
index 11343b8..9e25a71 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -805,6 +805,21 @@ impl<'a, A: Array> Drop for Drain<'a, A>
     }
 }
 
+struct ScopeExitGuard<T, Data, F>
+    where F: FnMut(&Data, &mut T)
+{
+    value: T,
+    data: Data,
+    f: F,
+}
+
+impl<T, Data, F> Drop for ScopeExitGuard<T, Data, F>
+    where F: FnMut(&Data, &mut T)
+{
+    fn drop(&mut self) {
+        (self.f)(&self.data, &mut self.value)
+    }
+}
 
 
 
@@ -815,9 +830,26 @@ impl<'a, A: Array> Drop for Drain<'a, A>
 impl<A: Array> Extend<A::Item> for ArrayVec<A> {
     fn extend<T: IntoIterator<Item=A::Item>>(&mut self, iter: T) {
         let take = self.capacity() - self.len();
-        for elt in iter.into_iter().take(take) {
-            unsafe {
-                self.push_unchecked(elt);
+        unsafe {
+            let len = self.len();
+            let mut ptr = self.as_mut_ptr().offset(len as isize);
+            // Keep the length in a separate variable, write it back on scope
+            // exit. To help the compiler with alias analysis and stuff.
+            // We update the length to handle panic in the iteration of the
+            // user's iterator, without dropping any elements on the floor.
+            let mut guard = ScopeExitGuard {
+                value: self,
+                data: len,
+                f: |&len, self_| {
+                    unsafe {
+                        self_.set_len(len)
+                    }
+                }
+            };
+            for elt in iter.into_iter().take(take) {
+                ptr::write(ptr, elt);
+                ptr = ptr.offset(1);
+                guard.data += 1;
             }
         }
     }