diff --git a/gnu/packages/python-xyz.scm b/gnu/packages/python-xyz.scm
index 0a2875d628..5f99073d93 100644
--- a/gnu/packages/python-xyz.scm
+++ b/gnu/packages/python-xyz.scm
@@ -20481,9 +20481,8 @@ (define-public python2-send2trash
           `(modify-phases ,phases
              (add-before 'check 'setenv
                (lambda _
-                 (setenv "PYTHONPATH"
-                         (string-append (getcwd) ":" (getenv "PYTHONPATH")))
-                 #t)))))))))
+                 (setenv "GUIX_PYTHONPATH"
+                         (string-append (getcwd) ":" (getenv "GUIX_PYTHONPATH"))))))))))))
 
 (define-public python-pyfavicon
   (package