diff --git a/src/Shader/Poke.hs b/src/Shader/Poke.hs
index ff6fb8316..b275d536b 100644
--- a/src/Shader/Poke.hs
+++ b/src/Shader/Poke.hs
@@ -91,6 +91,9 @@ pokeShapeE eptr ieptr (nv,n,ni,nei) (V3 a b c) = do
     pokeElemOff ieptr nei (fromIntegral n)
     return $ (nv,n + 1,ni,nei+1)
 
+topPrismEdgeIndices :: Int -> [Int]
+topPrismEdgeIndices n = undefined
+
 topPrismIndices :: Int -> [Int]
 topPrismIndices n = concatMap f [1..n-2]    -- triangles on top face
     ++ [2*n-2,2*n-1,1