diff --git a/app/pdb/image-sample-points-cmds.c b/app/pdb/image-sample-points-cmds.c
index 1a17fafbca..be57dc069e 100644
--- a/app/pdb/image-sample-points-cmds.c
+++ b/app/pdb/image-sample-points-cmds.c
@@ -298,13 +298,13 @@ register_image_sample_points_procs (GimpPDB *pdb)
                                g_param_spec_uint ("sample-point",
                                                   "sample point",
                                                   "The ID of the current sample point (0 if first invocation)",
-                                                  1, G_MAXUINT32, 1,
+                                                  0, G_MAXUINT32, 0,
                                                   GIMP_PARAM_READWRITE | GIMP_PARAM_NO_VALIDATE));
   gimp_procedure_add_return_value (procedure,
                                    g_param_spec_uint ("next-sample-point",
                                                       "next sample point",
                                                       "The next sample point's ID",
-                                                      1, G_MAXUINT32, 1,
+                                                      0, G_MAXUINT32, 0,
                                                       GIMP_PARAM_READWRITE));
   gimp_pdb_register_procedure (pdb, procedure);
   g_object_unref (procedure);
diff --git a/pdb/app.pl b/pdb/app.pl
index fec21aadae..4acca8daa9 100644
--- a/pdb/app.pl
+++ b/pdb/app.pl
@@ -481,11 +481,12 @@ g_param_spec_uint ("$name",
 CODE
     }
     elsif ($pdbtype eq 'sample_point') {
+        $min = exists $arg->{none_ok} ? 0 : 1,
 	$pspec = <<CODE;
 g_param_spec_uint ("$name",
                    "$nick",
                    "$blurb",
-                   1, G_MAXUINT32, 1,
+                   $min, G_MAXUINT32, $min,
                    $flags)
 CODE
     }
diff --git a/pdb/groups/image_sample_points.pdb b/pdb/groups/image_sample_points.pdb
index 21fce3eee4..e2d243d114 100644
--- a/pdb/groups/image_sample_points.pdb
+++ b/pdb/groups/image_sample_points.pdb
@@ -109,12 +109,12 @@ HELP
     @inargs = (
 	{ name => 'image', type => 'image',
 	  desc => 'The image' },
-	{ name => 'sample_point', type => 'sample_point', no_validate => 1,
+	{ name => 'sample_point', type => 'sample_point', no_validate => 1, none_ok => 1,
 	  desc => 'The ID of the current sample point (0 if first invocation)' }
     );
 
     @outargs = (
-	{ name => 'next_sample_point', type => 'sample_point',
+	{ name => 'next_sample_point', type => 'sample_point', none_ok => 1,
 	  desc => "The next sample point's ID" }
     );
 
diff --git a/pdb/lib.pl b/pdb/lib.pl
index 272d2f2c59..438539f4f4 100644
--- a/pdb/lib.pl
+++ b/pdb/lib.pl
@@ -139,7 +139,8 @@ sub generate_fun {
             $retarg_len = $retarg->{array}->{name};
             $annotate   = " (array length=$retarg_len)";
         }
-        if (exists $retarg->{none_ok}) {
+
+        if (exists $retarg->{none_ok} && $type ne 'sample_point') {
             $annotate .= " (nullable)";
         }
 
@@ -199,6 +200,7 @@ sub generate_fun {
         my $desc = exists $_->{desc} ? $_->{desc} : "";
         my $var_len;
         my $value;
+        my $n_annotations = 0;
 
         if (exists $_->{nopdb}) {
             $argc--;
@@ -284,16 +286,20 @@ sub generate_fun {
 
         if (exists $arg->{array}) {
             $argdesc .= " (array length=$var_len)";
+            $n_annotations++;
         }
 
         if (exists $arg->{in_annotate}) {
             $argdesc .= " $arg->{in_annotate}";
-        }
-        if (exists $_->{none_ok}) {
-            $argdesc .= " (nullable)";
+            $n_annotations++;
         }
 
-        if (exists $arg->{array} || exists $_->{none_ok} || exists $arg->{in_annotate}) {
+        if (exists $_->{none_ok} && $type ne 'sample_point') {
+            $argdesc .= " (nullable)";
+            $n_annotations++;
+        }
+
+        if ($n_annotations > 0) {
             $argdesc .= ":";
         }