diff --git a/Basis/ERI.ml b/Basis/ERI.ml
index d275ed9..7d67fb0 100644
--- a/Basis/ERI.ml
+++ b/Basis/ERI.ml
@@ -158,12 +158,12 @@ let of_basis basis =
             (* Compute all the integrals of the class *)
             let cls =
               if swap then
-                if (Array.length sp) + (Array.length sq)  = 2 then
+                if (Array.length sp) + (Array.length sq)  < 4 then 
                   contracted_class_shell_pairs ~schwartz_p:schwartz_q ~schwartz_q:schwartz_p shell_q shell_p 
                 else
                   contracted_class_shell_pairs_vec ~schwartz_p:schwartz_q ~schwartz_q:schwartz_p shell_q shell_p 
               else
-                if (Array.length sp) + (Array.length sq)  = 2 then
+                if (Array.length sp) + (Array.length sq)  < 4 then 
                   contracted_class_shell_pairs ~schwartz_p ~schwartz_q shell_p shell_q 
                 else
                   contracted_class_shell_pairs_vec ~schwartz_p ~schwartz_q shell_p shell_q