diff --git a/pkgs/development/python2-modules/wcwidth/default.nix b/pkgs/development/python2-modules/wcwidth/default.nix
index 8424fa462503..023b92a86907 100644
--- a/pkgs/development/python2-modules/wcwidth/default.nix
+++ b/pkgs/development/python2-modules/wcwidth/default.nix
@@ -3,7 +3,7 @@
 }:
 
 wcwidth.overridePythonAttrs(oldAttrs: {
-  propagatedBuildInputs = oldAttrs.propagatedBuildInputs ++ [
+  propagatedBuildInputs = oldAttrs.propagatedBuildInputs or [] ++ [
     backports-functools-lru-cache
   ];
 })