diff --git a/python-sphinxcontrib-serializinghtml.spec b/python-sphinxcontrib-serializinghtml.spec
index cd9d263..8f35677 100644
--- a/python-sphinxcontrib-serializinghtml.spec
+++ b/python-sphinxcontrib-serializinghtml.spec
@@ -1,6 +1,6 @@
 Name:          python-sphinxcontrib-serializinghtml
 Version:       1.1.5
-Release:       1mamba
+Release:       2mamba
 Summary:       A sphinx extension which outputs "serialized" HTML files (json and pickle)
 Group:         System/Libraries
 Vendor:        openmamba
@@ -17,6 +17,8 @@ BuildRequires: libpython3-devel
 %{summary}.
 
 %if 0%{?with_pyver}
+%define py_requires_append \
+Obsoletes:     python-sphinxcontrib-serializinghtml < 1.1.5
 %pyver_package
 %endif
 
@@ -44,6 +46,9 @@ sed -i "\,\.egg-info/,d;s,.*/man/.*,&.gz," %{name}.filelist
 %doc LICENSE
 
 %changelog
+* Tue Jun 01 2021 Silvan Calarco <silvan.calarco@mambasoft.it> 1.1.5-2mamba
+- obsolete python-sphinxcontrib-serializinghtml
+
 * Sun May 30 2021 Silvan Calarco <silvan.calarco@mambasoft.it> 1.1.5-1mamba
 - update to 1.1.5