diff --git a/tool/src/org/antlr/v4/tool/GrammarTransformPipeline.java b/tool/src/org/antlr/v4/tool/GrammarTransformPipeline.java
index db1084052..cc41130f3 100644
--- a/tool/src/org/antlr/v4/tool/GrammarTransformPipeline.java
+++ b/tool/src/org/antlr/v4/tool/GrammarTransformPipeline.java
@@ -358,12 +358,14 @@ public class GrammarTransformPipeline {
 		// add strings from combined grammar (and imported grammars) into lexer
 		// put them first as they are keywords; must resolve ambigs to these rules
 //		tool.log("grammar", "strings from parser: "+stringLiterals);
-nextLit:
+		nextLit:
 		for (String lit : stringLiterals) {
 			// if lexer already has a rule for literal, continue
-			for (Pair<GrammarAST,GrammarAST> pair : litAliases) {
-				GrammarAST litAST = pair.b;
-				if ( lit.equals(litAST.getText()) ) continue nextLit;
+			if ( litAliases!=null ) {
+				for (Pair<GrammarAST,GrammarAST> pair : litAliases) {
+					GrammarAST litAST = pair.b;
+					if ( lit.equals(litAST.getText()) ) continue nextLit;
+				}
 			}
 			// create for each literal: (RULE <uniquename> (BLOCK (ALT <lit>))
 			String rname = combinedGrammar.getStringLiteralLexerRuleName(lit);
diff --git a/tool/src/org/antlr/v4/tool/interp/LexerInterpreter.java b/tool/src/org/antlr/v4/tool/interp/LexerInterpreter.java
index f48e72944..c38be3ca0 100644
--- a/tool/src/org/antlr/v4/tool/interp/LexerInterpreter.java
+++ b/tool/src/org/antlr/v4/tool/interp/LexerInterpreter.java
@@ -38,6 +38,8 @@ import org.antlr.v4.runtime.Token;
 import org.antlr.v4.runtime.TokenFactory;
 import org.antlr.v4.runtime.TokenSource;
 import org.antlr.v4.runtime.atn.LexerATNSimulator;
+import org.antlr.v4.runtime.atn.PredictionContextCache;
+import org.antlr.v4.runtime.dfa.DFA;
 import org.antlr.v4.tool.LexerGrammar;
 
 public class LexerInterpreter implements TokenSource {
@@ -48,6 +50,10 @@ public class LexerInterpreter implements TokenSource {
 	/** How to create token objects */
 	protected TokenFactory<?> _factory = CommonTokenFactory.DEFAULT;
 
+	protected static final DFA[] _decisionToDFA = new DFA[1];
+	protected static final PredictionContextCache _sharedContextCache =
+		new PredictionContextCache();
+
 	public LexerInterpreter(LexerGrammar g, String inputString) {
 		this(g);
 		setInput(inputString);
@@ -56,7 +62,7 @@ public class LexerInterpreter implements TokenSource {
 	public LexerInterpreter(LexerGrammar g) {
 		Tool antlr = new Tool();
 		antlr.process(g,false);
-		interp = new LexerATNSimulator(g.atn,null,null);
+		interp = new LexerATNSimulator(g.atn,_decisionToDFA,_sharedContextCache);
 	}
 
 	public void setInput(String inputString) {
diff --git a/tool/test/org/antlr/v4/test/BaseTest.java b/tool/test/org/antlr/v4/test/BaseTest.java
index 6bd0e6ec7..f00818752 100644
--- a/tool/test/org/antlr/v4/test/BaseTest.java
+++ b/tool/test/org/antlr/v4/test/BaseTest.java
@@ -212,7 +212,7 @@ public abstract class BaseTest {
 									  CharStream input,
 									  boolean adaptive)
 	{
-		LexerATNSimulator interp = new LexerATNSimulator(atn,null,null);
+		LexerATNSimulator interp = new LexerATNSimulator(atn,new DFA[1],null);
 		List<String> tokenTypes = new ArrayList<String>();
 		int ttype;
 		boolean hitEOF = false;
diff --git a/tool/test/org/antlr/v4/test/TestATNInterpreter.java b/tool/test/org/antlr/v4/test/TestATNInterpreter.java
index 7f2e57b47..e6b36e42f 100644
--- a/tool/test/org/antlr/v4/test/TestATNInterpreter.java
+++ b/tool/test/org/antlr/v4/test/TestATNInterpreter.java
@@ -6,6 +6,7 @@ import org.antlr.v4.runtime.atn.ATN;
 import org.antlr.v4.runtime.atn.ATNState;
 import org.antlr.v4.runtime.atn.BlockStartState;
 import org.antlr.v4.runtime.atn.LexerATNSimulator;
+import org.antlr.v4.runtime.dfa.DFA;
 import org.antlr.v4.runtime.misc.IntegerList;
 import org.antlr.v4.tool.DOTGenerator;
 import org.antlr.v4.tool.Grammar;
@@ -271,13 +272,11 @@ public class TestATNInterpreter extends BaseTest {
 								int expected)
 	{
 		ATN lexatn = createATN(lg);
-		LexerATNSimulator lexInterp = new LexerATNSimulator(lexatn,null,null);
+		LexerATNSimulator lexInterp = new LexerATNSimulator(lexatn,new DFA[1],null);
 		IntegerList types = getTokenTypesViaATN(inputString, lexInterp);
 		System.out.println(types);
 
-		semanticProcess(lg);
 		g.importVocab(lg);
-		semanticProcess(g);
 
 		ParserATNFactory f = new ParserATNFactory(g);
 		ATN atn = f.createATN();