diff --git a/pkgs/development/python-modules/psycopg/default.nix b/pkgs/development/python-modules/psycopg/default.nix
index 021393718212..e3e13ac78944 100644
--- a/pkgs/development/python-modules/psycopg/default.nix
+++ b/pkgs/development/python-modules/psycopg/default.nix
@@ -226,6 +226,7 @@ buildPythonPackage rec {
     "refcount"
     "timing"
     "flakey"
+    "slow"
   ];
 
   postCheck = ''