diff --git a/string.c b/string.c
index 52c52ab0b7..7f21f77cc2 100644
--- a/string.c
+++ b/string.c
@@ -2949,7 +2949,7 @@ rb_str_concat_literals(size_t num, const VALUE *strary)
  *  Concatenates the given object(s) to <i>str</i>. If an object is an
  *  <code>Integer</code>, it is considered a codepoint and converted
  *  to a character before concatenation.
- 
+
  *  +concat+ can take multiple arguments, and all the arguments are concatenated
  *  in order.  See String#<<, which takes a single argument.
  *