diff --git a/.gitignore b/.gitignore
index ae97dae..1c4a4b3 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,2 @@
 /ruamel.yaml.clib-0.1.2.tar.gz
+/ruamel-yaml-clib-code-955989c1f022b95ca1f92bf0abd761ef8aa0b940.zip
diff --git a/python-ruamel-yaml-clib.spec b/python-ruamel-yaml-clib.spec
index 24f80b4..c76c63d 100644
--- a/python-ruamel-yaml-clib.spec
+++ b/python-ruamel-yaml-clib.spec
@@ -1,14 +1,17 @@
 %global pypi_name ruamel.yaml.clib
 %global pname ruamel-yaml-clib
 
+# This means version 0.1.2:
+%global hash 955989c1f022b95ca1f92bf0abd761ef8aa0b940
+
 Name:           python-%{pname}
 Version:        0.1.2
-Release:        4%{?dist}
+Release:        5%{?dist}
 Summary:        C version of reader, parser and emitter for ruamel.yaml derived from libyaml
 
 License:        MIT
 URL:            https://bitbucket.org/ruamel/yaml.clib
-Source0:        %{pypi_source}
+Source0:        https://sourceforge.net/code-snapshots/hg/r/ru/ruamel-yaml-clib/code/ruamel-yaml-clib-code-%{hash}.zip
 
 BuildRequires:  gcc
 BuildRequires:  libyaml-devel
@@ -20,6 +23,7 @@ It is the C based reader/scanner and emitter for ruamel.yaml.
 Summary:        %{summary}
 BuildRequires:  python3-devel
 BuildRequires:  python3-setuptools
+BuildRequires:  python3-Cython
 
 Requires:       python3-setuptools
 
@@ -27,9 +31,18 @@ Requires:       python3-setuptools
 It is the C based reader/scanner and emitter for ruamel.yaml.
 
 %prep
-%autosetup -n %{pypi_name}-%{version}
+%autosetup -n %{pname}-code-%{hash}
+# Force regenerating C files from Cython sources
+rm -v $(grep -rl '/\* Generated by Cython')
 
 %build
+# cython refuses to cythonize a file in a directory that cannot be a Python module ¯\_(ツ)_/¯
+mkdir ruamel.yaml.clib
+mv *.pyx ruamel.yaml.clib
+cythonize ruamel.yaml.clib/*.pyx
+mv ruamel.yaml.clib/* .
+rmdir ruamel.yaml.clib
+
 %py3_build
 
 %install
@@ -42,6 +55,9 @@ It is the C based reader/scanner and emitter for ruamel.yaml.
 %{python3_sitearch}/%{pypi_name}-%{version}-py%{python3_version}.egg-info
 
 %changelog
+* Thu Nov 12 2020 Miro Hrončok <mhroncok@redhat.com> - 0.1.2-5
+- Force regenerating C files from Cython sources
+
 * Wed Jul 29 2020 Fedora Release Engineering <releng@fedoraproject.org> - 0.1.2-4
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_33_Mass_Rebuild
 
diff --git a/sources b/sources
index 7fa9a8f..c4c4d35 100644
--- a/sources
+++ b/sources
@@ -1 +1 @@
-SHA512 (ruamel.yaml.clib-0.1.2.tar.gz) = a5c84b1ff10dde5a467fa16f1a3bd5ea174c39251364429ac3d63fa94bc728571316a8f418bf9a50f441096d59580c3e2e49c3ecf9d5961d650d61440b57f461
+SHA512 (ruamel-yaml-clib-code-955989c1f022b95ca1f92bf0abd761ef8aa0b940.zip) = a2032af5c677c5ebadd8c8289bd0fa926cbb07e0a289d95893dc7f0e38d6387cf3798046727627c6574ede84828054eabf6262b4f5a490072e8902c85c6c6b06