diff --git a/org.hl7.fhir.utilities/src/main/java/org/hl7/fhir/utilities/i18n/I18nConstants.java b/org.hl7.fhir.utilities/src/main/java/org/hl7/fhir/utilities/i18n/I18nConstants.java
index 7c3d3a5bd..761ae9178 100644
--- a/org.hl7.fhir.utilities/src/main/java/org/hl7/fhir/utilities/i18n/I18nConstants.java
+++ b/org.hl7.fhir.utilities/src/main/java/org/hl7/fhir/utilities/i18n/I18nConstants.java
@@ -566,5 +566,6 @@ public class I18nConstants {
   public static final String FHIRPATH_DISCRIMINATOR_MULTIPLE_TYPES = "FHIRPATH_DISCRIMINATOR_MULTIPLE_TYPES";
   public static final String FHIRPATH_DISCRIMINATOR_MULTIPLE_PROFILES = "FHIRPATH_DISCRIMINATOR_MULTIPLE_PROFILES";
   public static final String FHIRPATH_UNABLE_BOOLEAN = "FHIRPATH_UNABLE_BOOLEAN";
+  public static final String XHTML_XHTML_DOCTYPE_ILLEGAL = "XHTML_XHTML_DOCTYPE_ILLEGAL";
 }
 
diff --git a/org.hl7.fhir.utilities/src/main/resources/Messages.properties b/org.hl7.fhir.utilities/src/main/resources/Messages.properties
index 820194d27..abc5b4c53 100644
--- a/org.hl7.fhir.utilities/src/main/resources/Messages.properties
+++ b/org.hl7.fhir.utilities/src/main/resources/Messages.properties
@@ -566,3 +566,5 @@ FHIRPATH_DISCRIMINATOR_NOTYPE = Error in discriminator at {0}: no children, no t
 FHIRPATH_DISCRIMINATOR_MULTIPLE_TYPES = Error in discriminator at {0}: no children, multiple types
 FHIRPATH_DISCRIMINATOR_MULTIPLE_PROFILES = Error in discriminator at {0}: no children, multiple type profiles
 FHIRPATH_UNABLE_BOOLEAN = Unable to evaluate as a boolean: {0} 
+XHTML_XHTML_DOCTYPE_ILLEGAL = Malformed XHTML: Found a DocType declaration, and these are not allowed (XXE security vulnerability protection)
+