1 files changed, 1 insertions, 1 deletions

diff --git a/src/macfns.c b/src/macfns.c
index 04cedba11dc..2b3ed8ae977 100644
--- a/src/macfns.c
+++ b/src/macfns.c
@@ -3114,7 +3114,7 @@ validate_x_resource_name ()
              || (c >= 'A' && c <= 'Z')
              || (c >= '0' && c <= '9')
              || c == '-' || c == '_'))
-        SREF (new, i) = '_';
+        SSET (new, i, '_');
     }
 }