diff --git a/src/lib.rs b/src/lib.rs
index 2d9747c48fc06874584c5f723e70320895bd1aac..edaf567c109a5968b89ae354516194474ba66a98 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -125,6 +125,7 @@ impl<T, A> Vec<T, A>
             unsafe {
                 *slice.as_mut_ptr().offset(self.len as isize) = elem;
             }
+            self.len += 1;
             Ok(())
         }
     }