diff --git a/python-Twisted.changes b/python-Twisted.changes
index fa1e3f8..d29b1f9 100644
--- a/python-Twisted.changes
+++ b/python-Twisted.changes
@@ -1,3 +1,8 @@
+-------------------------------------------------------------------
+Mon Oct 22 08:48:37 UTC 2018 - Tomáš Chvátal <tchvatal@suse.com>
+
+- Do not write bytecode stuff when running the tests
+
 -------------------------------------------------------------------
 Fri Oct 19 13:27:25 UTC 2018 - Matěj Cepl <mcepl@suse.com>
 
diff --git a/python-Twisted.spec b/python-Twisted.spec
index a4c8b97..0dae566 100644
--- a/python-Twisted.spec
+++ b/python-Twisted.spec
@@ -121,7 +121,7 @@ install -dm0755 %{buildroot}%{_mandir}/man1/
 install -m0644 docs/*/man/*.1 %{buildroot}%{_mandir}/man1/ # Install man pages
 find docs -type f -print0 | xargs -0 chmod a-x # Fix doc-file dependency by removing x flags
 #sed -i "s/\r//" docs/core/howto/listings/udp/{MulticastClient,MulticastServer}.py
-%python_expand %fdupes %{buildroot}%{$python_sitelib}
+%python_expand %fdupes %{buildroot}%{$python_sitearch}
 
 # Prepare for update-alternatives usage
 for p in twistd cftp ckeygen conch pyhtmlizer tkconch trial ; do
@@ -140,6 +140,7 @@ done
 %check
 export LANG=en_US.UTF-8
 export PATH=%{buildroot}%{_bindir}:$PATH
+export PYTHONDONTWRITEBYTECODE=1
 %python_expand PYTHONPATH=%{buildroot}%{$python_sitearch} $python -m twisted.trial twisted
 
 %files -n %{name}-doc