Fbackward_prefix_chars: stay within buffer bounds

[gnu-emacs] / src / syntax.c

diff --git a/src/syntax.c b/src/syntax.c
index 0af2a21a220477b539acd2e492463a1093a1496e..6e133ad9c279628446978237cb847bed2a68bc37 100644 (file)
--- a/src/syntax.c
+++ b/src/syntax.c
@@ -3098,8 +3098,9 @@ the prefix syntax flag (p).  */)
       opoint = pos;
       opoint_byte = pos_byte;
 
-      if (pos + 1 > beg)
-       DEC_BOTH (pos, pos_byte);
+      if (pos <= beg)
+        break;
+      DEC_BOTH (pos, pos_byte);
     }
 
   SET_PT_BOTH (opoint, opoint_byte);