diff --git a/Basis/ContractedShellPair.ml b/Basis/ContractedShellPair.ml
index c34b105..69428ed 100644
--- a/Basis/ContractedShellPair.ml
+++ b/Basis/ContractedShellPair.ml
@@ -87,8 +87,8 @@ let create ?cutoff p_a p_b =
                 Cs.(center p_a = center p_b)
               in
               let totAngMomInt = 
-                Am.to_int (Cs.totAngMom p_a) +
-                Am.to_int (Cs.totAngMom p_b)
+                Am.(Cs.totAngMom p_a + Cs.totAngMom p_b)
+                |> Am.to_int
               in
               Some {
                 Sp.i ; j ;
diff --git a/Basis/OneElectronRR.ml b/Basis/OneElectronRR.ml
index a7d800c..640f4a3 100644
--- a/Basis/OneElectronRR.ml
+++ b/Basis/OneElectronRR.ml
@@ -101,7 +101,8 @@ let contracted_class_shell_pair ~zero_m shell_p geometry : float Zmap.t =
   and shell_b = Csp.shell_b shell_p
   in
   let maxm = 
-    Am.to_int (Cs.totAngMom shell_a) + Am.to_int (Cs.totAngMom shell_b) 
+    Am.(Cs.totAngMom shell_a + Cs.totAngMom shell_b) 
+    |> Am.to_int
   in
 
   (* Pre-computation of integral class indices *)
diff --git a/Utils/AngularMomentum.ml b/Utils/AngularMomentum.ml
index fea8c85..bcea44b 100644
--- a/Utils/AngularMomentum.ml
+++ b/Utils/AngularMomentum.ml
@@ -144,3 +144,10 @@ let zkey_array a =
     Hashtbl.add zkey_array_memo a result;
     result
 
+
+let ( + ) a b =
+  of_int ( (to_int a) + (to_int b) )
+
+let ( - ) a b =
+  of_int ( (to_int a) - (to_int b) )
+
diff --git a/Utils/AngularMomentum.mli b/Utils/AngularMomentum.mli
index e71efec..2ed7a8f 100644
--- a/Utils/AngularMomentum.mli
+++ b/Utils/AngularMomentum.mli
@@ -85,3 +85,7 @@ val zkey_array : kind -> Zkey.t array
   ]}
 
   *)
+
+val ( + ) : t -> t -> t
+val ( - ) : t -> t -> t
+