Panic in default methods. Fixes #68
diff --git a/src/lib.rs b/src/lib.rs
index e524560..ae60563 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -268,7 +268,7 @@
 
 impl Default for BigEndian {
     fn default() -> BigEndian {
-        unreachable!()
+        panic!("BigEndian default")
     }
 }
 
@@ -281,7 +281,7 @@
 
 impl Default for LittleEndian {
     fn default() -> LittleEndian {
-        unreachable!()
+        panic!("LittleEndian default")
     }
 }