diff --git a/setup.cfg b/setup.cfg
index 5f7b828e9c1ff5fec021659b68d5657d350f7466..768163ca8a71a5f9f8efc5f7020ad57bff10b28b 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -43,8 +43,9 @@ install_requires =
     Twisted[tls,conch] >= 19.10.0
 
     # Tahoe has no stable Python API but we use its Python API so there's
-    # basically no wiggle room here.
-    tahoe-lafs == 1.17.0
+    # basically no wiggle room here.  We still use a (really tiny) range
+    # because our Nix packaging provides a Tahoe-LAFS with a .postNNN version.
+    tahoe-lafs >=1.17.0,<1.17.1
     treq
     pyutil
     prometheus-client