diff --git a/process.c b/process.c
index aaea02a0f808c6..681535d92fd452 100644
--- a/process.c
+++ b/process.c
@@ -910,7 +910,7 @@ pst_bitand(VALUE st1, VALUE st2)
  *     stat >> 1                 # => 128
  *     stat >> 2                 # => 64
  *
- *  Returns zero if +places+ is negative.
+ *  The behavior is unspecified if +places+ is negative.
  */
 
 static VALUE