diff --git a/org/qmckl_jastrow_champ.org b/org/qmckl_jastrow_champ.org
index b26970c..c76d59c 100644
--- a/org/qmckl_jastrow_champ.org
+++ b/org/qmckl_jastrow_champ.org
@@ -794,7 +794,7 @@ qmckl_set_jastrow_champ_c_vector(qmckl_context context,
 
   if (size_max < dim_c_vector*type_nucl_num) {
     char msg[256];
-    sprintf(msg, "Array too small. Expected dim_c_vector*type_nucl_num = %ld",
+    sprintf(msg, "Array too small. Expected dim_c_vector*type_nucl_num = %lld",
             dim_c_vector*type_nucl_num );
     return qmckl_failwith( context,
                            QMCKL_INVALID_ARG_3,