diff --git a/org/qmckl_ao.org b/org/qmckl_ao.org
index b193f3a..b307c65 100644
--- a/org/qmckl_ao.org
+++ b/org/qmckl_ao.org
@@ -1871,6 +1871,13 @@ qmckl_exit_code qmckl_provide_ao_basis_shell_vgl(qmckl_context context)
                            "qmckl_ao_basis_shell_vgl",
                            NULL);
   }
+
+  if(!(ctx->electron.provided)) {
+    return qmckl_failwith( context,
+                           QMCKL_NOT_PROVIDED,
+                           "qmckl_electron",
+                           NULL);
+  }
   
   /* Compute if necessary */
   if (ctx->electron.coord_new_date > ctx->ao_basis.shell_vgl_date) {