diff --git a/plugins/Full_CI_ZMQ/selection.irp.f b/plugins/Full_CI_ZMQ/selection.irp.f
index 82276406..3da1bca4 100644
--- a/plugins/Full_CI_ZMQ/selection.irp.f
+++ b/plugins/Full_CI_ZMQ/selection.irp.f
@@ -5,7 +5,7 @@ BEGIN_PROVIDER [ integer, fragment_count ]
   BEGIN_DOC
   ! Number of fragments for the deterministic part
   END_DOC
-  fragment_count = (elec_alpha_num-n_core_orb)**2
+  fragment_count = (elec_alpha_num-n_core_orb)*mo_tot_num
 END_PROVIDER