diff --git a/org/qmckl_mo.org b/org/qmckl_mo.org
index e13cbc5..2914c62 100644
--- a/org/qmckl_mo.org
+++ b/org/qmckl_mo.org
@@ -377,6 +377,13 @@ qmckl_exit_code qmckl_provide_mo_vgl(qmckl_context context)
                            NULL);
   }
   
+  if (!ctx->mo_basis.provided) {
+    return qmckl_failwith( context,
+                           QMCKL_NOT_PROVIDED,
+                           "qmckl_mo_basis",
+                           NULL);
+  }
+
   /* Compute if necessary */
   if (ctx->electron.coord_new_date > ctx->mo_basis.mo_vgl_date) {