diff --git a/pkgs/tools/security/stacs/default.nix b/pkgs/tools/security/stacs/default.nix
index 672cd082849c..205d85f0622e 100644
--- a/pkgs/tools/security/stacs/default.nix
+++ b/pkgs/tools/security/stacs/default.nix
@@ -20,7 +20,7 @@ python3.pkgs.buildPythonApplication rec {
 
   propagatedBuildInputs = with python3.pkgs; [
     click
-    pydantic
+    pydantic_1
     typing-extensions
     yara-python
   ];