diff --git a/m-string.h b/m-string.h
index c306a986..e3ed8acf 100644
--- a/m-string.h
+++ b/m-string.h
@@ -1842,6 +1842,7 @@ m_string_previous(m_string_it_t it)
       bool b = m_string_end_p(it);
       M_ASSERT(!b);
       (void) b;
+      return;
     }
   }
   /* We reach the start of the string: mark the iterator to the end */
diff --git a/tests/test-mstring.c b/tests/test-mstring.c
index 7b28844d..0b08e8a8 100644
--- a/tests/test-mstring.c
+++ b/tests/test-mstring.c
@@ -119,6 +119,7 @@ static void test_utf8_it(void)
     i--;
     assert (string_get_cref(it) == tab[i]);
   }
+  assert(i == 0);
 
   string_set_str (s, "H€llo René Chaînôr¬");
   assert(string_length_u(s) == 19);