diff --git a/ChangeLog b/ChangeLog
index 4d49f9aa8..4a4c09a56 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
 2003-11-03  Alexandre Duret-Lutz  <adl@src.lip6.fr>
 
+	* iface/gspn/gspn.cc
+	(tgba_gspn_eesrg_private_::tgba_gspn_eesrg_private_): Show prop_index()
+	and prop_kind() arguments on error.
+
 	* iface/gspn/eesrg.cc
 	(tgba_gspn_eesrg_private_::tgba_gspn_eesrg_private_): Show prop_index()
 	argument on error.
diff --git a/iface/gspn/gspn.cc b/iface/gspn/gspn.cc
index 606610e52..17856f227 100644
--- a/iface/gspn/gspn.cc
+++ b/iface/gspn/gspn.cc
@@ -100,11 +100,11 @@ namespace spot
 	      AtomicProp index;
 	      int err = prop_index(i->first.c_str(), &index);
 	      if (err)
-		throw gspn_exeption("prop_index()", err);
+		throw gspn_exeption("prop_index(" + i->first + ")", err);
 	      AtomicPropKind kind;
 	      err = prop_kind(index, &kind);
 	      if (err)
-		throw gspn_exeption("prop_kind()", err);
+		throw gspn_exeption("prop_kind(" + i->first + ")", err);
 
 	      prop_dict[index] = ab_pair(kind, bdd_ithvar(var));
 	    }