1 files changed, 3 insertions, 0 deletions

diff --git a/src/buffer.c b/src/buffer.c
index 9d5fb51c258..0cd234303f6 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -1735,6 +1735,9 @@ but the contents viewed as characters do change.")
 {
   Lisp_Object tail, markers;
 
+  if (current_buffer->base_buffer)
+    error ("Cannot do `set-buffer-multibyte' on an indirect buffer");
+
   /* Do nothing if nothing actually changes.  */
   if (NILP (flag) == NILP (current_buffer->enable_multibyte_characters))
     return flag;