diff --git a/src/main/java/com/github/fge/jsonschema/exceptions/InvalidInstanceException.java b/src/main/java/com/github/fge/jsonschema/exceptions/InvalidInstanceException.java
index f50d10a70..ef609b49b 100644
--- a/src/main/java/com/github/fge/jsonschema/exceptions/InvalidInstanceException.java
+++ b/src/main/java/com/github/fge/jsonschema/exceptions/InvalidInstanceException.java
@@ -28,6 +28,8 @@
 public final class InvalidInstanceException
     extends ProcessingException
 {
+    private static final long serialVersionUID = -3273787152985150466L;
+
     public InvalidInstanceException(final ProcessingMessage message)
     {
         super(message);
diff --git a/src/main/java/com/github/fge/jsonschema/format/common/DateTimeAttribute.java b/src/main/java/com/github/fge/jsonschema/format/common/DateTimeAttribute.java
index 20a4a9821..8aae60ad2 100644
--- a/src/main/java/com/github/fge/jsonschema/format/common/DateTimeAttribute.java
+++ b/src/main/java/com/github/fge/jsonschema/format/common/DateTimeAttribute.java
@@ -31,8 +31,6 @@
 import org.joda.time.format.DateTimeFormatterBuilder;
 import org.joda.time.format.DateTimeParser;
 
-import java.util.List;
-
 import static org.joda.time.DateTimeFieldType.*;
 
 /**
@@ -41,7 +39,7 @@
 public final class DateTimeAttribute
     extends AbstractFormatAttribute
 {
-    private static final List<String> FORMATS = ImmutableList.of(
+    private static final ImmutableList<String> FORMATS = ImmutableList.of(
         "yyyy-MM-dd'T'HH:mm:ssZ", "yyyy-MM-dd'T'HH:mm:ss.[0-9]{1,12}Z"
     );
     private static final DateTimeFormatter FORMATTER;
diff --git a/src/main/java/com/github/fge/jsonschema/format/common/RFC3339DateTimeAttribute.java b/src/main/java/com/github/fge/jsonschema/format/common/RFC3339DateTimeAttribute.java
index 80a42ae75..73c1e12af 100644
--- a/src/main/java/com/github/fge/jsonschema/format/common/RFC3339DateTimeAttribute.java
+++ b/src/main/java/com/github/fge/jsonschema/format/common/RFC3339DateTimeAttribute.java
@@ -1,7 +1,5 @@
 package com.github.fge.jsonschema.format.common;
 
-import java.util.List;
-
 import com.github.fge.jsonschema.cfg.ValidationConfiguration;
 import com.github.fge.jsonschema.library.DraftV4Library;
 import org.joda.time.format.DateTimeFormatter;
@@ -31,7 +29,7 @@
  */
 public class RFC3339DateTimeAttribute extends AbstractFormatAttribute {
 
-	private static final List<String> RFC3339_FORMATS = ImmutableList.of(
+	private static final ImmutableList<String> RFC3339_FORMATS = ImmutableList.of(
 	        "yyyy-MM-dd'T'HH:mm:ss((+|-)HH:mm|Z)", "yyyy-MM-dd'T'HH:mm:ss.[0-9]{1,12}((+|-)HH:mm|Z)"
 	    );
 	
diff --git a/src/main/java/com/github/fge/jsonschema/format/common/RegexAttribute.java b/src/main/java/com/github/fge/jsonschema/format/common/RegexAttribute.java
index 9db53adee..f20127c19 100644
--- a/src/main/java/com/github/fge/jsonschema/format/common/RegexAttribute.java
+++ b/src/main/java/com/github/fge/jsonschema/format/common/RegexAttribute.java
@@ -22,7 +22,7 @@
 import com.github.fge.jackson.NodeType;
 import com.github.fge.jsonschema.core.exceptions.ProcessingException;
 import com.github.fge.jsonschema.core.report.ProcessingReport;
-import com.github.fge.jsonschema.core.util.RhinoHelper;
+import com.github.fge.jsonschema.core.util.RegexECMA262Helper;
 import com.github.fge.jsonschema.format.AbstractFormatAttribute;
 import com.github.fge.jsonschema.format.FormatAttribute;
 import com.github.fge.jsonschema.processors.data.FullData;
@@ -34,7 +34,7 @@
  * <p>Again, here, we do <b>not</b> use {@link java.util.regex} because it does
  * not fit the bill.</p>
  *
- * @see RhinoHelper
+ * @see RegexECMA262Helper
  */
 public final class RegexAttribute
     extends AbstractFormatAttribute
@@ -58,7 +58,7 @@ public void validate(final ProcessingReport report,
     {
         final String value = data.getInstance().getNode().textValue();
 
-        if (!RhinoHelper.regexIsValid(value))
+        if (!RegexECMA262Helper.regexIsValid(value))
             report.error(newMsg(data, bundle, "err.format.invalidRegex")
                 .putArgument("value", value));
     }
diff --git a/src/main/java/com/github/fge/jsonschema/keyword/digest/draftv3/DraftV3DependenciesDigester.java b/src/main/java/com/github/fge/jsonschema/keyword/digest/draftv3/DraftV3DependenciesDigester.java
index 386bb07bb..683dc962d 100644
--- a/src/main/java/com/github/fge/jsonschema/keyword/digest/draftv3/DraftV3DependenciesDigester.java
+++ b/src/main/java/com/github/fge/jsonschema/keyword/digest/draftv3/DraftV3DependenciesDigester.java
@@ -91,6 +91,9 @@ public JsonNode digest(final JsonNode schema)
                 case STRING:
                     propertyDeps.put(key, FACTORY.arrayNode()
                         .add(value.textValue()));
+                    break;
+                default:
+                    break;
             }
         }
 
diff --git a/src/main/java/com/github/fge/jsonschema/keyword/validator/common/AdditionalPropertiesValidator.java b/src/main/java/com/github/fge/jsonschema/keyword/validator/common/AdditionalPropertiesValidator.java
index b466ba678..1741dad02 100644
--- a/src/main/java/com/github/fge/jsonschema/keyword/validator/common/AdditionalPropertiesValidator.java
+++ b/src/main/java/com/github/fge/jsonschema/keyword/validator/common/AdditionalPropertiesValidator.java
@@ -25,7 +25,7 @@
 import com.github.fge.jsonschema.core.exceptions.ProcessingException;
 import com.github.fge.jsonschema.core.processing.Processor;
 import com.github.fge.jsonschema.core.report.ProcessingReport;
-import com.github.fge.jsonschema.core.util.RhinoHelper;
+import com.github.fge.jsonschema.core.util.RegexECMA262Helper;
 import com.github.fge.jsonschema.keyword.validator.AbstractKeywordValidator;
 import com.github.fge.jsonschema.processors.data.FullData;
 import com.github.fge.msgsimple.bundle.MessageBundle;
@@ -84,7 +84,7 @@ public void validate(final Processor<FullData, FullData> processor,
 
         for (final String field: fields)
             for (final String regex: patternProperties)
-                if (RhinoHelper.regMatch(regex, field))
+                if (RegexECMA262Helper.regMatch(regex, field))
                     tmp.add(field);
 
         fields.removeAll(tmp);
diff --git a/src/main/java/com/github/fge/jsonschema/keyword/validator/common/PatternValidator.java b/src/main/java/com/github/fge/jsonschema/keyword/validator/common/PatternValidator.java
index 653428a27..5bce7ea79 100644
--- a/src/main/java/com/github/fge/jsonschema/keyword/validator/common/PatternValidator.java
+++ b/src/main/java/com/github/fge/jsonschema/keyword/validator/common/PatternValidator.java
@@ -23,7 +23,7 @@
 import com.github.fge.jsonschema.core.exceptions.ProcessingException;
 import com.github.fge.jsonschema.core.processing.Processor;
 import com.github.fge.jsonschema.core.report.ProcessingReport;
-import com.github.fge.jsonschema.core.util.RhinoHelper;
+import com.github.fge.jsonschema.core.util.RegexECMA262Helper;
 import com.github.fge.jsonschema.keyword.validator.AbstractKeywordValidator;
 import com.github.fge.jsonschema.processors.data.FullData;
 import com.github.fge.msgsimple.bundle.MessageBundle;
@@ -31,7 +31,7 @@
 /**
  * Keyword validator for {@code pattern}
  *
- * @see RhinoHelper
+ * @see RegexECMA262Helper
  */
 public final class PatternValidator
     extends AbstractKeywordValidator
@@ -50,7 +50,7 @@ public void validate(final Processor<FullData, FullData> processor,
         final String regex = data.getSchema().getNode().get(keyword)
             .textValue();
         final String value = data.getInstance().getNode().textValue();
-        if (!RhinoHelper.regMatch(regex, value))
+        if (!RegexECMA262Helper.regMatch(regex, value))
             report.error(newMsg(data, bundle, "err.common.pattern.noMatch")
                 .putArgument("regex", regex).putArgument("string", value));
     }
diff --git a/src/main/java/com/github/fge/jsonschema/main/cli/CustomHelpFormatter.java b/src/main/java/com/github/fge/jsonschema/main/cli/CustomHelpFormatter.java
index 95c6eaa4a..752fd7bb3 100644
--- a/src/main/java/com/github/fge/jsonschema/main/cli/CustomHelpFormatter.java
+++ b/src/main/java/com/github/fge/jsonschema/main/cli/CustomHelpFormatter.java
@@ -34,7 +34,7 @@
 final class CustomHelpFormatter
     implements HelpFormatter
 {
-    private static final List<String> HELP_PREAMBLE = ImmutableList.of(
+    private static final ImmutableList<String> HELP_PREAMBLE = ImmutableList.of(
         "Syntax:",
         "    java -jar jsonschema.jar [options] schema file [file...]",
         "    java -jar jsonschema.jar --syntax [options] schema [schema...]",
@@ -42,7 +42,7 @@ final class CustomHelpFormatter
         "Options: "
     );
 
-    private static final List<String> HELP_POST
+    private static final ImmutableList<String> HELP_POST
         = ImmutableList.<String>builder()
         .add("")
         .add("Exit codes:")
diff --git a/src/main/java/com/github/fge/jsonschema/processors/validation/ObjectSchemaSelector.java b/src/main/java/com/github/fge/jsonschema/processors/validation/ObjectSchemaSelector.java
index 91e63a10a..9ddc1f3bb 100644
--- a/src/main/java/com/github/fge/jsonschema/processors/validation/ObjectSchemaSelector.java
+++ b/src/main/java/com/github/fge/jsonschema/processors/validation/ObjectSchemaSelector.java
@@ -21,7 +21,7 @@
 
 import com.fasterxml.jackson.databind.JsonNode;
 import com.github.fge.jackson.jsonpointer.JsonPointer;
-import com.github.fge.jsonschema.core.util.RhinoHelper;
+import com.github.fge.jsonschema.core.util.RegexECMA262Helper;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Lists;
 
@@ -73,7 +73,7 @@ public Iterable<JsonPointer> selectSchemas(final String memberName)
             list.add(PROPERTIES.append(memberName));
 
         for (final String regex: patternProperties)
-            if (RhinoHelper.regMatch(regex, memberName))
+            if (RegexECMA262Helper.regMatch(regex, memberName))
                 list.add(PATTERNPROPERTIES.append(regex));
 
         if (!list.isEmpty())
diff --git a/src/main/java/com/github/fge/jsonschema/processors/validation/ValidationStack.java b/src/main/java/com/github/fge/jsonschema/processors/validation/ValidationStack.java
index 0759cb87f..ea31f1730 100644
--- a/src/main/java/com/github/fge/jsonschema/processors/validation/ValidationStack.java
+++ b/src/main/java/com/github/fge/jsonschema/processors/validation/ValidationStack.java
@@ -58,12 +58,6 @@
 @ParametersAreNonnullByDefault
 final class ValidationStack
 {
-    /*
-     * Sentinel which is always the first element of the stack; we use it in
-     * order to simplify the pop code.
-     */
-    private static final Element NULL_ELEMENT = new Element(null, null);
-
     /*
      * Queue of visited contexts
      */
diff --git a/src/test/java/com/github/fge/jsonschema/keyword/validator/callback/CallbackValidatorTest.java b/src/test/java/com/github/fge/jsonschema/keyword/validator/callback/CallbackValidatorTest.java
index d5d936e94..92ada83b5 100644
--- a/src/test/java/com/github/fge/jsonschema/keyword/validator/callback/CallbackValidatorTest.java
+++ b/src/test/java/com/github/fge/jsonschema/keyword/validator/callback/CallbackValidatorTest.java
@@ -21,7 +21,7 @@
 
 import static com.github.fge.jsonschema.TestUtils.anyReport;
 import static com.github.fge.jsonschema.TestUtils.onlyOnce;
-import static org.mockito.Matchers.any;
+import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.spy;
 import static org.mockito.Mockito.times;
@@ -247,6 +247,7 @@ private DummyProcessor(final WantedState wanted1,
         }
 
         @Override
+        @SuppressWarnings("ReferenceEquality")
         public FullData process(final ProcessingReport report,
             final FullData input)
             throws ProcessingException