diff --git a/mercurial/util.py b/mercurial/util.py
--- a/mercurial/util.py
+++ b/mercurial/util.py
@@ -1209,6 +1209,9 @@ def matchdate(date):
             days = int(date[1:])
         except ValueError:
             raise Abort(_("invalid day spec: %s") % date[1:])
+        if days < 0:
+            raise Abort(_("%s must be nonnegative (see 'hg help dates')")
+                % date[1:])
         when = makedate()[0] - days * 3600 * 24
         return lambda x: x >= when
     elif " to " in date:
diff --git a/tests/test-log.t b/tests/test-log.t
--- a/tests/test-log.t
+++ b/tests/test-log.t
@@ -534,6 +534,11 @@ log -d "<"
   abort: invalid day spec, use '<DATE'
   [255]
 
+Negative ranges
+  $ hg log -d "--2"
+  abort: -2 must be nonnegative (see 'hg help dates')
+  [255]
+
 
 log -p -l2 --color=always