diff --git a/src/main/java/com/rometools/opml/io/impl/OPML20Generator.java b/src/main/java/com/rometools/opml/io/impl/OPML20Generator.java
index a774291..b83379b 100644
--- a/src/main/java/com/rometools/opml/io/impl/OPML20Generator.java
+++ b/src/main/java/com/rometools/opml/io/impl/OPML20Generator.java
@@ -88,7 +88,7 @@ public class OPML20Generator extends OPML10Generator {
             }
         }
         final String categoryString = builder.toString();
-        if (categoryString == null || categoryString.trim().isEmpty()) {
+        if (categoryString == null || categoryString.isEmpty()) {
             return null;
         } else {
             return categoryString;