diff --git a/pkgs/top-level/python-packages.nix b/pkgs/top-level/python-packages.nix
index 34c098a437ad..074ae294d119 100644
--- a/pkgs/top-level/python-packages.nix
+++ b/pkgs/top-level/python-packages.nix
@@ -23572,7 +23572,7 @@ in modules // {
       sha256 = "0k7vk4k54y55ma0nx2k5s0phfqbriwslhy5shh3b0d046q7ibzaa";
     };
 
-    buildInputs = with self; [ flask jinja2 speaklater Babel pytz ];
+    propagatedBuildInputs = with self; [ flask jinja2 speaklater Babel pytz ];
 
     meta = {
       description = "Adds i18n/l10n support to Flask applications";