diff --git a/hgext/releasenotes.py b/hgext/releasenotes.py
--- a/hgext/releasenotes.py
+++ b/hgext/releasenotes.py
@@ -25,6 +25,7 @@
     error,
     minirst,
     node,
+    pycompat,
     registrar,
     scmutil,
     util,
@@ -570,6 +571,8 @@
     admonitions along with their title. This also includes the custom
     admonitions (if any).
     """
+
+    opts = pycompat.byteskwargs(opts)
     sections = releasenotessections(ui, repo)
 
     listflag = opts.get('list')