diff --git a/doc/build.py b/doc/build.py
index bd10aa84..c25f588a 100755
--- a/doc/build.py
+++ b/doc/build.py
@@ -31,7 +31,7 @@ def create_build_env(venv_dir='virtualenv'):
   # Jinja2 >= 3.1 incompatible with sphinx 3.3.0
   # See: https://github.com/sphinx-doc/sphinx/issues/10291
   pip.install('Jinja2<3.1')
-  pip.install('sphinx-doc/sphinx', 'v3.3.0')
+  pip.install('sphinx==3.3.0')
   pip.install('michaeljones/breathe', 'v4.25.0')
 
 def build_docs(version='dev', **kwargs):
diff --git a/support/manage.py b/support/manage.py
index 0e116010..7f0c25a7 100755
--- a/support/manage.py
+++ b/support/manage.py
@@ -243,11 +243,12 @@ def release(args):
         elif line.startswith('#'):
             first_section = False
         elif first_section:
-            changes += line
+            changes_line = line
             if re.match(r'^\s*```', line):
                 code_block = not code_block
             elif not code_block and line != '\n':
-                changes = changes.rstrip() + ' '
+                changes_line = line.rstrip() + ' '
+            changes += changes_line
         sys.stdout.write(line)
 
     cmakelists = 'CMakeLists.txt'