diff --git a/source/utf8/core.h b/source/utf8/core.h
index 693d388..ae0f367 100644
--- a/source/utf8/core.h
+++ b/source/utf8/core.h
@@ -222,6 +222,9 @@ namespace internal
     template <typename octet_iterator>
     utf_error validate_next(octet_iterator& it, octet_iterator end, uint32_t& code_point)
     {
+	if (it == end)
+            return NOT_ENOUGH_ROOM;
+
         // Save the original value of it so we can go back in case of failure
         // Of course, it does not make much sense with i.e. stream iterators
         octet_iterator original_it = it;