diff --git a/libz.spec b/libz.spec
index 5e2c79a..394db92 100644
--- a/libz.spec
+++ b/libz.spec
@@ -1,6 +1,6 @@
 Name:          libz
 Version:       1.2.11
-Release:       2mamba
+Release:       3mamba
 Summary:       The zlib compression and decompression library
 Group:         System/Libraries
 Vendor:        openmamba
@@ -17,6 +17,9 @@ Provides:      zlib = %{version}-%{release}
 ## AUTOBUILDREQ-BEGIN
 BuildRequires: glibc-devel
 ## AUTOBUILDREQ-END
+%ifarch x86_64
+Obsoletes:     lib32-libz
+%endif
 BuildRoot:     %{_tmppath}/%{name}-%{version}-root
 
 %description
@@ -192,6 +195,9 @@ cd ../..
 #%endif
 
 %changelog
+* Thu Jan 16 2020 Silvan Calarco <silvan.calarco@mambasoft.it> 1.2.11-3mamba
+- x86_64: obsolete lib32-libz
+
 * Sun Sep 30 2018 Silvan Calarco <silvan.calarco@mambasoft.it> 1.2.11-2mamba
 - move library from /%{_lib} to %{_libdir}