(Fread_file_name): Check type of DEFAULT_FILENAME.

1 files changed, 4 insertions, 1 deletions

diff --git a/src/fileio.c b/src/fileio.c
index 893073d9cd7..702d9ac1299 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -5451,7 +5451,10 @@ DIR defaults to current buffer's directory default.")
       XSTRING (default_filename)->data[0] = '~';
     }
   if (!NILP (default_filename))
-    default_filename = double_dollars (default_filename);
+    {
+      CHECK_STRING (default_filename, 3);
+      default_filename = double_dollars (default_filename);
+    }
 
   if (insert_default_directory && STRINGP (dir))
     {