diff -urN a/c/src/xalanc/PlatformSupport/XalanLocator.hpp b/c/src/xalanc/PlatformSupport/XalanLocator.hpp
--- a/c/src/xalanc/PlatformSupport/XalanLocator.hpp	2012-09-27 07:59:33.000000000 +0100
+++ b/c/src/xalanc/PlatformSupport/XalanLocator.hpp	2018-09-07 16:07:11.070819930 +0100
@@ -91,7 +91,7 @@
             const XalanDOMChar*     theAlternateId = getEmptyPtr())
     {
         return theLocator == 0 ? theAlternateId : (theLocator->getSystemId() ?
-            theLocator->getPublicId() : theAlternateId);
+            theLocator->getSystemId() : theAlternateId);
     }
 
     /**
