diff --git a/mercurial/revset.py b/mercurial/revset.py
--- a/mercurial/revset.py
+++ b/mercurial/revset.py
@@ -241,7 +241,8 @@ def tokenize(program, lookup=None, symin
                 yield ('symbol', sym, s)
             pos -= 1
         else:
-            raise error.ParseError(_("syntax error"), pos)
+            raise error.ParseError(_("syntax error in revset '%s'") %
+                                   program, pos)
         pos += 1
     yield ('end', None, pos)
 
diff --git a/tests/test-revset.t b/tests/test-revset.t
--- a/tests/test-revset.t
+++ b/tests/test-revset.t
@@ -1535,7 +1535,7 @@ test in problematic encoding
 
 test error message of bad revset
   $ hg log -r 'foo\\'
-  hg: parse error at 3: syntax error
+  hg: parse error at 3: syntax error in revset 'foo\\'
   [255]
 
   $ cd ..