diff --git a/test/runner/requirements/constraints.txt b/test/runner/requirements/constraints.txt
index de0fbcbb99b..46eeeb64d93 100644
--- a/test/runner/requirements/constraints.txt
+++ b/test/runner/requirements/constraints.txt
@@ -17,3 +17,6 @@ ntlm-auth >= 1.0.6 # message encryption support
 requests-ntlm >= 1.1.0 # message encryption support
 requests-credssp >= 0.1.0 # message encryption support
 voluptuous >= 0.11.0 # Schema recursion via Self
+virtualenv < 16.0.0 ; python_version < '2.7' # virtualenv 16.0.0 and later require python 2.7 or later
+pyopenssl < 18.0.0 ; python_version < '2.7' # pyOpenSSL 18.0.0 and later require python 2.7 or later
+pyfmg == 0.6.1 # newer versions do not pass current unit tests