diff --git a/graphics/birdfont/README b/graphics/birdfont/README
index 54074a257d..cc8b8f6a0b 100644
--- a/graphics/birdfont/README
+++ b/graphics/birdfont/README
@@ -2,3 +2,9 @@ Birdfont is a free font editor which lets you create vector graphics
 and export TTF, OTF and SVG fonts. 
 The editor has good support for both monochrome and color font 
 formats. 
+
+Version 2.33.3 is the latest can be installed in Slackware 15.0 because
+earlier versions require webkit2gtk4.1. Since the build of Birdfont is
+based on vala and the version 0.54 available in Slackware 15.0 does not
+create the APIs for webkit2gtk 4.1, the build of version earlier than 
+2.33.3 will fail.