diff --git a/perturbation/mp2.org b/perturbation/mp2.org
index 60dfa24..4bf9a51 100644
--- a/perturbation/mp2.org
+++ b/perturbation/mp2.org
@@ -171,10 +171,11 @@ let tests =
 
       let frozen_core = Mo.Frozen_core.(make Small nuclei) in
 
-      let e_mp2 = Perturbation.Mp2.make ~frozen_core mo_basis in
+      let mp2 = Perturbation.Mp2.make ~frozen_core mo_basis in
+
+      let e_mp2 = Perturbation.Mp2.energy mp2 in
 
       check (float 1.e-9) "MP2" (-0.2016211415) (e_mp2)
   ]
-    
    #+end_src
    
diff --git a/perturbation/test/mp2.ml b/perturbation/test/mp2.ml
index dc0c022..2c7e5bb 100644
--- a/perturbation/test/mp2.ml
+++ b/perturbation/test/mp2.ml
@@ -31,7 +31,9 @@ let tests =
 
       let frozen_core = Mo.Frozen_core.(make Small nuclei) in
 
-      let e_mp2 = Perturbation.Mp2.make ~frozen_core mo_basis in
+      let mp2 = Perturbation.Mp2.make ~frozen_core mo_basis in
+
+      let e_mp2 = Perturbation.Mp2.energy mp2 in
 
       check (float 1.e-9) "MP2" (-0.2016211415) (e_mp2)
   ]