diff --git a/saml-core/src/main/java/org/keycloak/saml/processing/core/saml/v2/writers/SAMLMetadataWriter.java b/saml-core/src/main/java/org/keycloak/saml/processing/core/saml/v2/writers/SAMLMetadataWriter.java
index 81ad6d82e4..072703b7ea 100755
--- a/saml-core/src/main/java/org/keycloak/saml/processing/core/saml/v2/writers/SAMLMetadataWriter.java
+++ b/saml-core/src/main/java/org/keycloak/saml/processing/core/saml/v2/writers/SAMLMetadataWriter.java
@@ -351,7 +351,9 @@ public class SAMLMetadataWriter extends BaseWriter {
         StaxUtil.writeStartElement(writer, METADATA_PREFIX, JBossSAMLConstants.ATTRIBUTE_CONSUMING_SERVICE.get(),
                 JBossSAMLURIConstants.METADATA_NSURI.get());
 
-        StaxUtil.writeAttribute(writer, JBossSAMLConstants.ISDEFAULT.get(), "" + attributeConsumer.isIsDefault());
+        if (attributeConsumer.isIsDefault() != null)
+           StaxUtil.writeAttribute(writer, JBossSAMLConstants.ISDEFAULT.get(), "" + attributeConsumer.isIsDefault());
+
         StaxUtil.writeAttribute(writer, JBossSAMLConstants.INDEX.get(), "" + attributeConsumer.getIndex());
 
         // Service Name
@@ -561,4 +563,4 @@ public class SAMLMetadataWriter extends BaseWriter {
 
         StaxUtil.writeEndElement(writer);
     }
-}
\ No newline at end of file
+}