diff --git a/include/libsemigroups/detail/word-iterators.hpp b/include/libsemigroups/detail/word-iterators.hpp
index 8a4cbbf22..9e8e0f88b 100644
--- a/include/libsemigroups/detail/word-iterators.hpp
+++ b/include/libsemigroups/detail/word-iterators.hpp
@@ -18,8 +18,8 @@
 
 // This file contains declarations of the iterator classes for words.
 
-#ifndef LIBSEMIGROUPS_WORD_ITERATORS_HPP_
-#define LIBSEMIGROUPS_WORD_ITERATORS_HPP_
+#ifndef LIBSEMIGROUPS_DETAIL_WORD_ITERATORS_HPP_
+#define LIBSEMIGROUPS_DETAIL_WORD_ITERATORS_HPP_
 
 #include <vector>
 
@@ -156,4 +156,4 @@ namespace libsemigroups {
     }
   }  // namespace detail
 }  // namespace libsemigroups
-#endif
\ No newline at end of file
+#endif  // LIBSEMIGROUPS_DETAIL_WORD_ITERATORS_HPP_
diff --git a/src/detail/word-iterators.cpp b/src/detail/word-iterators.cpp
index cb225e245..66d02621c 100644
--- a/src/detail/word-iterators.cpp
+++ b/src/detail/word-iterators.cpp
@@ -149,4 +149,4 @@ namespace libsemigroups {
     static_assert(std::is_destructible<const_wislo_iterator>::value,
                   "forward iterator requires destructible");
   }  // namespace detail
-}  // namespace libsemigroups
\ No newline at end of file
+}  // namespace libsemigroups