diff --git a/fontbox/src/main/java/org/apache/fontbox/ttf/gsub/GlyphSubstitutionDataExtractor.java b/fontbox/src/main/java/org/apache/fontbox/ttf/gsub/GlyphSubstitutionDataExtractor.java
index 911b9aa3017..80d4af6c8fd 100644
--- a/fontbox/src/main/java/org/apache/fontbox/ttf/gsub/GlyphSubstitutionDataExtractor.java
+++ b/fontbox/src/main/java/org/apache/fontbox/ttf/gsub/GlyphSubstitutionDataExtractor.java
@@ -122,6 +122,7 @@ private ScriptTableDetails getSupportedLanguage(Map<String, ScriptTable> scriptL
                 ScriptTable value = scriptList.get(scriptName);
                 if (value != null)
                 {
+                    LOG.debug("Language decided: {} {}", lang, scriptName);
                     return new ScriptTableDetails(lang, scriptName, value);
                 }
             }