diff --git a/pkgs/applications/science/math/sage/default.nix b/pkgs/applications/science/math/sage/default.nix
index 6403b649af4..832b2f11056 100644
--- a/pkgs/applications/science/math/sage/default.nix
+++ b/pkgs/applications/science/math/sage/default.nix
@@ -110,6 +110,7 @@ let
     sympy
     fpylll
     matplotlib
+    tkinter # optional, as a matplotlib backend (use with `%matplotlib tk`)
     scipy
     ipywidgets
     rpy2