diff --git a/.ci/prep_azure.py b/.ci/prep_azure.py
index 80dbf485..fd8fb694 100755
--- a/.ci/prep_azure.py
+++ b/.ci/prep_azure.py
@@ -84,6 +84,12 @@ else:
 if need_to_fix_psycopg2:
     venv_steps.append('/tmp/venv/bin/pip3 install psycopg2==2.8.5 psycopg2-binary')
 
+venv_steps.extend([
+    # pbr is a transitive setup_requires of hdrhistogram. If it's not already
+    # installed then setuptools attempts to use easy_install, which fails.
+    '/tmp/venv/bin/pip install pbr==5.6.0',
+])
+
 batches.append(venv_steps)
 
 ci_lib.run_batches(batches)
diff --git a/tests/requirements.txt b/tests/requirements.txt
index 76e6545d..21ef8166 100644
--- a/tests/requirements.txt
+++ b/tests/requirements.txt
@@ -12,6 +12,7 @@ timeoutcontext==1.2.0
 unittest2==1.1.0
 # Fix InsecurePlatformWarning while creating py26 tox environment
 # https://urllib3.readthedocs.io/en/latest/advanced-usage.html#ssl-warnings
-urllib3[secure]; python_version < '2.7.9'
+urllib3[secure]==1.23; python_version < '2.7'
+urllib3[secure]==1.26; python_version > '2.6' and python_version < '2.7.9'
 # Last idna compatible with Python 2.6 was idna 2.7.
 idna==2.7; python_version < '2.7'