diff --git a/tools/pdbgen/pdb/color.pdb b/tools/pdbgen/pdb/color.pdb
index bea3fdd..0817916 100644
--- a/tools/pdbgen/pdb/color.pdb
+++ b/tools/pdbgen/pdb/color.pdb
@@ -556,9 +556,9 @@ HELP
 	  desc => 'The drawable' },
 	{ name => 'channel', type => 'enum GimpHistogramChannel',
 	  desc => 'The channel to modify' },
-	{ name => 'start_range', type => '0 <= int32 < 256',
+	{ name => 'start_range', type => '0 <= int32 <= 255',
 	  desc => 'Start of the intensity measurement range' },
-	{ name => 'end_range', type => '0 <= int32 < 256',
+	{ name => 'end_range', type => '0 <= int32 <= 255',
 	  desc => 'End of the intensity measurement range' }
     );
 
