diff --git a/app/pdb/drawable-filter-cmds.c b/app/pdb/drawable-filter-cmds.c
index 236a36d5e1..c6cfe11ab6 100644
--- a/app/pdb/drawable-filter-cmds.c
+++ b/app/pdb/drawable-filter-cmds.c
@@ -883,22 +883,14 @@ drawable_filter_operation_get_pspecs_invoker (GimpProcedure         *procedure,
             {
               GParamSpec *pspec     = specs[n_parent_specs + i];
               GPParamDef  param_def = { 0, };
+              GValue value = G_VALUE_INIT;
+
+              g_value_init (&value, G_TYPE_PARAM);
 
               /* Make sure we do not try to send param specs over the wire
                * if we don't support sending their type.
                */
-              if (_gimp_param_spec_to_gp_param_def (pspec, &param_def, TRUE))
-                {
-                  GValue value = G_VALUE_INIT;
-
-                  g_value_init (&value, G_TYPE_PARAM);
-
-                  g_value_set_param (&value, g_param_spec_ref (pspec));
-                  gimp_value_array_append (pspecs, &value);
-
-                  g_value_unset (&value);
-                }
-              else
+              if (! _gimp_param_spec_to_gp_param_def (pspec, &param_def, TRUE))
                 {
                   /* This is not technically a bug if an operation has
                    * unsupported argument types, because we cannot possibly
@@ -909,11 +901,27 @@ drawable_filter_operation_get_pspecs_invoker (GimpProcedure         *procedure,
                    * want to softly notify developers, in case we can
                    * actually do something about some types.
                    */
-                  g_printerr ("%s: ignoring argument '%s' of procedure '%s'. "
+                  g_printerr ("%s: replacing argument '%s' of procedure '%s' with a placeholder. "
                               "Unsupported argument type '%s'.\n",
                               G_STRFUNC, pspec->name, operation_name,
                               g_type_name (G_PARAM_SPEC_VALUE_TYPE (pspec)));
+
+                  g_value_set_param (&value, g_param_spec_param (
+                                      "unknown", "Unknown",
+                                      g_strdup_printf ("placeholder for unsupported type:%s:%s:%s",
+                                                 pspec->name,
+                                                 g_type_name (G_PARAM_SPEC_VALUE_TYPE (pspec)),
+                                                 g_param_spec_get_blurb (pspec)),
+                                      G_TYPE_PARAM, G_PARAM_READABLE | G_PARAM_STATIC_NICK | G_PARAM_STATIC_BLURB));
                 }
+              else
+                {
+                  g_value_set_param (&value, g_param_spec_ref (pspec));
+                }
+
+              gimp_value_array_append (pspecs, &value);
+
+              g_value_unset (&value);
             }
 
           g_free (specs);
diff --git a/pdb/groups/drawable_filter.pdb b/pdb/groups/drawable_filter.pdb
index 2f5570b55c..e8201d07ce 100644
--- a/pdb/groups/drawable_filter.pdb
+++ b/pdb/groups/drawable_filter.pdb
@@ -849,22 +849,14 @@ HELP
         {
           GParamSpec *pspec     = specs[n_parent_specs + i];
           GPParamDef  param_def = { 0, };
+          GValue value = G_VALUE_INIT;
+
+          g_value_init (&value, G_TYPE_PARAM);
 
           /* Make sure we do not try to send param specs over the wire
            * if we don't support sending their type.
            */
-          if (_gimp_param_spec_to_gp_param_def (pspec, &param_def, TRUE))
-            {
-              GValue value = G_VALUE_INIT;
-
-              g_value_init (&value, G_TYPE_PARAM);
-
-              g_value_set_param (&value, g_param_spec_ref (pspec));
-              gimp_value_array_append (pspecs, &value);
-
-              g_value_unset (&value);
-            }
-          else
+          if (! _gimp_param_spec_to_gp_param_def (pspec, &param_def, TRUE))
             {
               /* This is not technically a bug if an operation has
                * unsupported argument types, because we cannot possibly
@@ -875,11 +867,27 @@ HELP
                * want to softly notify developers, in case we can
                * actually do something about some types.
                */
-              g_printerr ("%s: ignoring argument '%s' of procedure '%s'. "
+              g_printerr ("%s: replacing argument '%s' of procedure '%s' with a placeholder. "
                           "Unsupported argument type '%s'.\n",
                           G_STRFUNC, pspec->name, operation_name,
                           g_type_name (G_PARAM_SPEC_VALUE_TYPE (pspec)));
+
+              g_value_set_param (&value, g_param_spec_param (
+                                  "unknown", "Unknown",
+                                  g_strdup_printf ("placeholder for unsupported type:%s:%s:%s",
+                                             pspec->name,
+                                             g_type_name (G_PARAM_SPEC_VALUE_TYPE (pspec)),
+                                             g_param_spec_get_blurb (pspec)),
+                                  G_TYPE_PARAM, G_PARAM_READABLE | G_PARAM_STATIC_NICK | G_PARAM_STATIC_BLURB));
             }
+          else
+            {
+              g_value_set_param (&value, g_param_spec_ref (pspec));
+            }
+
+          gimp_value_array_append (pspecs, &value);
+
+          g_value_unset (&value);
         }
 
       g_free (specs);