diff --git a/sax/src/main/java/org/openjax/xml/sax/XmlCatalogResolver.java b/sax/src/main/java/org/openjax/xml/sax/XmlCatalogResolver.java
index 392cd6c..a36504a 100644
--- a/sax/src/main/java/org/openjax/xml/sax/XmlCatalogResolver.java
+++ b/sax/src/main/java/org/openjax/xml/sax/XmlCatalogResolver.java
@@ -79,8 +79,14 @@ else if (XMLConstants.XML_NS_URI.equals(namespaceURI)) {
         }
       }
 
-      if (entity == null)
-        return new CachedInputSource(publicId, systemId, baseURI, new URL(systemId).openConnection());
+      if (entity == null) {
+        try {
+          return new CachedInputSource(publicId, systemId, baseURI, new URL(systemId).openConnection());
+        }
+        catch (final IOException e) {
+          return null;
+        }
+      }
 
       final CachedInputSource inputSource = entity.getInputSource();
       inputSource.getCharacterStream().close();
diff --git a/sax/src/test/java/org/openjax/xml/sax/FastSAXParserTest.java b/sax/src/test/java/org/openjax/xml/sax/FastSAXParserTest.java
index f6ab732..50d0f6c 100644
--- a/sax/src/test/java/org/openjax/xml/sax/FastSAXParserTest.java
+++ b/sax/src/test/java/org/openjax/xml/sax/FastSAXParserTest.java
@@ -25,7 +25,6 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Iterator;
-import java.util.List;
 
 import org.junit.Test;
 import org.libj.io.ReplayReader;
@@ -136,7 +135,7 @@ public boolean attribute(final int prefix, final int localName, final int skip,
     }
   };
 
-  private static void add(final List<? super Event> events, final Type type, final String ... fields) {
+  private static void add(final ArrayList<? super Event> events, final Type type, final String ... fields) {
     events.add(new Event(type, fields));
   }
 
@@ -155,7 +154,7 @@ private static void assertEvent(final Iterator<Event> iterator, final Reader in,
       assertEquals(event.fields[i], fields[i]);
   }
 
-  private static void test(final List<Event> events, final URL url) throws IOException, SAXParseException {
+  private static void test(final ArrayList<Event> events, final URL url) throws IOException, SAXParseException {
     final Iterator<Event> iterator = events.iterator();
     try (final Reader in = new ReplayReader(new InputStreamReader(url.openStream()))) {
       FastSAXParser.parse(in, new FasterTestHandler(iterator, in));
@@ -164,7 +163,7 @@ private static void test(final List<Event> events, final URL url) throws IOExcep
 
   @Test
   public void testTestXsd() throws IOException, SAXParseException {
-    final List<Event> events = new ArrayList<>();
+    final ArrayList<Event> events = new ArrayList<>();
     add(events, Type.DOST);
     add(events, Type.CMNT, "\n  Copyright (c) 2006 OpenJAX\n\n  Permission is hereby granted, free of charge, to any person obtaining a copy\n  of this software and associated documentation files (the \"Software\"), to deal\n  in the Software without restriction, including without limitation the rights\n  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell\n  copies of the Software, and to permit persons to whom the Software is\n  furnished to do so, subject to the following conditions:\n\n  The above copyright notice and this permission notice shall be included in\n  all copies or substantial portions of the Software.\n\n  You should have received a copy of The MIT License (MIT) along with this\n  program. If not, see <http://opensource.org/licenses/MIT/>.\n");
     add(events, Type.ELOP, "xs:", "schema");
@@ -289,7 +288,7 @@ public void testTestXsd() throws IOException, SAXParseException {
 
   @Test
   public void testNumeralsXml() throws IOException, SAXParseException {
-    final List<Event> events = new ArrayList<>();
+    final ArrayList<Event> events = new ArrayList<>();
     add(events, Type.DOST);
     add(events, Type.CMNT, "\n  Copyright (c) 2008 OpenJAX\n\n  Permission is hereby granted, free of charge, to any person obtaining a copy\n  of this software and associated documentation files (the \"Software\"), to deal\n  in the Software without restriction, including without limitation the rights\n  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell\n  copies of the Software, and to permit persons to whom the Software is\n  furnished to do so, subject to the following conditions:\n\n  The above copyright notice and this permission notice shall be included in\n  all copies or substantial portions of the Software.\n\n  You should have received a copy of The MIT License (MIT) along with this\n  program. If not, see <http://opensource.org/licenses/MIT/>.\n");
     add(events, Type.ELOP, "xs:", "schema");
@@ -333,7 +332,7 @@ public void testNumeralsXml() throws IOException, SAXParseException {
 
   @Test
   public void testDoctypeXml() throws IOException, SAXParseException {
-    final List<Event> events = new ArrayList<>();
+    final ArrayList<Event> events = new ArrayList<>();
     add(events, Type.DOST);
     add(events, Type.CMNT, "\n  Copyright (c) 2019 OpenJAX\n\n  Permission is hereby granted, free of charge, to any person obtaining a copy\n  of this software and associated documentation files (the \"Software\"), to deal\n  in the Software without restriction, including without limitation the rights\n  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell\n  copies of the Software, and to permit persons to whom the Software is\n  furnished to do so, subject to the following conditions:\n\n  The above copyright notice and this permission notice shall be included in\n  all copies or substantial portions of the Software.\n\n  You should have received a copy of The MIT License (MIT) along with this\n  program. If not, see <http://opensource.org/licenses/MIT/>.\n");
     add(events, Type.DOCT, "DOCTYPE catalog [\n  <!NOTATION jpeg SYSTEM \"JPG\">\n  <!ENTITY prod557 SYSTEM \"prod557.jpg\" NDATA jpeg>\n  <!ENTITY prod563 SYSTEM \"prod563.jpg\" NDATA jpeg>\n]");