1 files changed, 2 insertions, 1 deletions

diff --git a/src/buffer.c b/src/buffer.c
index c649836adb8..46e8ddf1538 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -5551,7 +5551,8 @@ Linefeed indents to this column in Fundamental mode.  */);
 
   DEFVAR_PER_BUFFER ("tab-width", &BVAR (current_buffer, tab_width),
                      make_number (LISP_INT_TAG),
-                     doc: /* *Distance between tab stops (for display of tab characters), in columns.  */);
+                     doc: /* *Distance between tab stops (for display of tab characters), in columns.
+This should be an integer greater than zero.  */);
 
   DEFVAR_PER_BUFFER ("ctl-arrow", &BVAR (current_buffer, ctl_arrow), Qnil,
                      doc: /* *Non-nil means display control chars with uparrow.