diff --git a/src/main/java/org/expath/tools/saxon/model/SaxonSequence.java b/src/main/java/org/expath/tools/saxon/model/SaxonSequence.java
index d969cb6..7f81ce5 100644
--- a/src/main/java/org/expath/tools/saxon/model/SaxonSequence.java
+++ b/src/main/java/org/expath/tools/saxon/model/SaxonSequence.java
@@ -110,7 +110,7 @@ private Properties makeOutputProperties(SerialParameters params)
         setOutputKey(props, SaxonOutputKeys.INCLUDE_CONTENT_TYPE,  params.getIncludeContentType());
         setOutputKey(props, SaxonOutputKeys.NORMALIZATION_FORM,    params.getNormalizationForm());
         setOutputKey(props, SaxonOutputKeys.UNDECLARE_PREFIXES,    params.getUndeclarePrefixes());
-        if ( params.getUseCharacterMaps() != null ) {
+        if ( params.getUseCharacterMaps() != null && params.getUseCharacterMaps().iterator().hasNext() ) {
             // TODO: How are we supposed to pass this param through a string property?
             throw new ToolsException("Use character map serialization parameter is not supported");
         }