diff --git a/src/OrbitDecomposition.jl b/src/OrbitDecomposition.jl
index fb58045..9adff7b 100644
--- a/src/OrbitDecomposition.jl
+++ b/src/OrbitDecomposition.jl
@@ -39,14 +39,6 @@ function orbit_spvector(vect::AbstractVector, orbits)
     return orb_vector
 end
 
-function orbit_constraint(constraints::Vector{Vector{Int}}, n)
-    result = spzeros(n,n)
-    for cnstr in constraints
-        result[cnstr] += 1.0/length(constraints)
-    end
-    return result
-end
-
 ###############################################################################
 #
 #  Matrix-, Permutation- and C*-representations
diff --git a/src/SDPs.jl b/src/SDPs.jl
index 279ca66..5c9fa1f 100644
--- a/src/SDPs.jl
+++ b/src/SDPs.jl
@@ -7,14 +7,15 @@ function constraints(pm::Matrix{I}, total_length=maximum(pm)) where {I<:Integer}
     return cnstrs
 end
 
-function constraint(pm::Matrix{I}, k) where {I<:Integer}
-    cnstr = Vector{I}()
-    for i in eachindex(pm)
-        if pm[i] == k
-            push!(cnstr, i)
+function orbit_constraint!(result::SparseMatrixCSC, cnstrs, orbit; val=1.0/length(orbit))
+    result .= zero(eltype(result))
+    dropzeros!(result)
+    for constraint in cnstr_orbit
+        for idx in constraint
+            result[idx] = val
         end
     end
-    return cnstr
+    return result
 end