diff --git a/engine-proto/gram-test/sphere-in-tetrahedron.jl b/engine-proto/gram-test/sphere-in-tetrahedron.jl
index ed1adfc..3730390 100644
--- a/engine-proto/gram-test/sphere-in-tetrahedron.jl
+++ b/engine-proto/gram-test/sphere-in-tetrahedron.jl
@@ -3,6 +3,7 @@ include("Engine.jl")
 using SparseArrays
 using AbstractAlgebra
 using PolynomialRoots
+using Random
 
 # initialize the partial gram matrix for a sphere inscribed in a regular
 # tetrahedron