diff --git a/.azure-pipelines.yml b/.azure-pipelines.yml
index 02970df9e1..2019573954 100644
--- a/.azure-pipelines.yml
+++ b/.azure-pipelines.yml
@@ -42,6 +42,7 @@ jobs:
 
   - script: |
       python -m pip install --upgrade pip
+      pip install -r .pip-2033.txt
       pip install pytest-cov wheel
       pip install .[dev,doc,test,louvain,leiden,magic,scvi,harmony,scrublet,scanorama]
     displayName: 'Install dependencies'
@@ -102,6 +103,7 @@ jobs:
     displayName: 'Display installed versions'
 
   - script: |
+      pip install flit
       flit build
       twine check dist/*
     displayName: 'Build & Twine check'
diff --git a/.pip-2033.txt b/.pip-2033.txt
new file mode 100644
index 0000000000..3c5aa646e0
--- /dev/null
+++ b/.pip-2033.txt
@@ -0,0 +1,4 @@
+# Flit mangles the +local part of the version spec in compliance with PEP 427,
+# but pip 20.3.4 started expecting wheel filenames to contain the local part unmangled.
+# https://github.com/pypa/pip/issues/9628
+pip==20.3.3
diff --git a/.readthedocs.yml b/.readthedocs.yml
index 58e2487826..de089915c5 100644
--- a/.readthedocs.yml
+++ b/.readthedocs.yml
@@ -6,6 +6,7 @@ sphinx:
 python:
   version: 3.8
   install:
+  - requirements: .pip-2033.txt
   - method: pip
     path: .
     extra_requirements: