diff --git a/tox.ini b/tox.ini
index 6c7150d9f..be50eefcb 100644
--- a/tox.ini
+++ b/tox.ini
@@ -20,9 +20,11 @@ passenv = TAHOE_LAFS_* PIP_* SUBUNITREPORTER_* USERPROFILE HOMEDRIVE HOMEPATH
 # available to those systems.  Installing it ahead of time (with pip) avoids
 # this problem.
 deps =
-     pip>8.1.1,<19
+     pip==19.1.1
+     setuptools==41.0.1
+     wheel==0.33.4
+     subunitreporter==19.3.2
      certifi
-     subunitreporter
 # We add usedevelop=True for speed, and extras=test to get things like "mock"
 # that are required for our unit tests.
 usedevelop = True