diff --git a/src/ReachSets/ContinuousPost/BFFPSV18/reach.jl b/src/ReachSets/ContinuousPost/BFFPSV18/reach.jl
index e600ec22..f4482539 100644
--- a/src/ReachSets/ContinuousPost/BFFPSV18/reach.jl
+++ b/src/ReachSets/ContinuousPost/BFFPSV18/reach.jl
@@ -78,7 +78,8 @@ function reach(problem::Union{IVP{<:CLDS{NUM}, <:LazySet{NUM}},
     if output_function == nothing
         res_type = SparseReachSet{CartesianProductArray{NUM, LazySet{NUM}}}
     else
-        res_type = SparseReachSet{Hyperrectangle{NUM}}
+        # by default, this algorithm uses box overapproximation
+        res_type = SparseReachSet{Hyperrectangle{NUM, Vector{NUM}, Vector{NUM}}}
     end
     res = (N == nothing) ? Vector{res_type}() : Vector{res_type}(undef, N)
 
diff --git a/test/Reachability/solve_continuous.jl b/test/Reachability/solve_continuous.jl
index 2fd24452..590b3bfc 100644
--- a/test/Reachability/solve_continuous.jl
+++ b/test/Reachability/solve_continuous.jl
@@ -72,6 +72,10 @@ s = solve(IVP(LCS(A), X0),
 # Test reachability options
 # ===============================
 
+# projection matrix
+M = [1.0 0.0 0.0 0.0; 0.0 1.0 0.0 0.0]
+s = solve(IVP(LCS(A), X0), Options(:T=>1.0, :projection_matrix=>M), op=BFFPSV18(:δ=>0.1))
+
 # template directions
 s = solve(IVP(LCS(A), X0),
           Options(:T=>0.1, :ε_proj=>1e-5, :set_type_proj=>HPolygon),