diff --git a/tool/src/org/antlr/v4/Tool.java b/tool/src/org/antlr/v4/Tool.java
index e39b22d1c..52f7d7b19 100644
--- a/tool/src/org/antlr/v4/Tool.java
+++ b/tool/src/org/antlr/v4/Tool.java
@@ -433,10 +433,16 @@ public class Tool {
 	public boolean checkForRuleIssues(final Grammar g) {
 		// check for redefined rules
 		GrammarAST RULES = (GrammarAST)g.ast.getFirstChildWithType(ANTLRParser.RULES);
-		List<RuleAST> rules = (List<RuleAST>)RULES.getChildren();
+
+		List<?> rules = (List<?>)RULES.getChildren();
+		if (rules == null) {
+			rules = Collections.emptyList();
+		}
+
 		final Map<String, RuleAST> ruleToAST = new HashMap<String, RuleAST>();
-		for (RuleAST r : rules) {
-			GrammarAST ID = (GrammarAST)r.getChild(0);
+		for (Object r : rules) {
+			RuleAST ruleAST = (RuleAST)r;
+			GrammarAST ID = (GrammarAST)ruleAST.getChild(0);
 			String ruleName = ID.getText();
 			RuleAST prev = ruleToAST.get(ruleName);
 			if ( prev !=null ) {
@@ -446,10 +452,10 @@ public class Tool {
 										   ID.getToken(),
 										   ruleName,
 										   prevChild.getToken().getLine());
-				r.dead = true;
+				ruleAST.dead = true;
 				continue;
 			}
-			ruleToAST.put(ruleName, r);
+			ruleToAST.put(ruleName, ruleAST);
 		}
 
 		// check for undefined rules
@@ -457,6 +463,11 @@ public class Tool {
 			public boolean undefined = false;
 			@Override
 			public void tokenRef(TerminalAST ref) {
+				if ("EOF".equals(ref.getText())) {
+					// this is a special predefined reference
+					return;
+				}
+
 				if ( g.isLexer() ) ruleRef(ref, null);
 			}
 
diff --git a/tool/src/org/antlr/v4/parse/ANTLRLexer.g b/tool/src/org/antlr/v4/parse/ANTLRLexer.g
index 6e01ae71f..446d5aac6 100644
--- a/tool/src/org/antlr/v4/parse/ANTLRLexer.g
+++ b/tool/src/org/antlr/v4/parse/ANTLRLexer.g
@@ -298,15 +298,16 @@ ARG_ACTION
 //
 ACTION
 	:	NESTED_ACTION
-		('?' {$type = SEMPRED;} )?
-		(	'=>' // v3 gated sempred
-			{
-			Token t = new CommonToken(input, state.type, state.channel, state.tokenStartCharIndex, getCharIndex()-1);
-			t.setLine(state.tokenStartLine);
-			t.setText(state.text);
-			t.setCharPositionInLine(state.tokenStartCharPositionInLine);
-            grammarError(ErrorType.V3_GATED_SEMPRED, t);
-			}
+		(	'?' {$type = SEMPRED;}
+			(	(WSNLCHARS* '=>') => WSNLCHARS* '=>' // v3 gated sempred
+				{
+				Token t = new CommonToken(input, state.type, state.channel, state.tokenStartCharIndex, getCharIndex()-1);
+				t.setLine(state.tokenStartLine);
+				t.setText(state.text);
+				t.setCharPositionInLine(state.tokenStartCharPositionInLine);
+				grammarError(ErrorType.V3_GATED_SEMPRED, t);
+				}
+			)?
 		)?
 	;
 
diff --git a/tool/src/org/antlr/v4/semantics/BasicSemanticChecks.java b/tool/src/org/antlr/v4/semantics/BasicSemanticChecks.java
index f4793a63b..0ef42fcd8 100644
--- a/tool/src/org/antlr/v4/semantics/BasicSemanticChecks.java
+++ b/tool/src/org/antlr/v4/semantics/BasicSemanticChecks.java
@@ -347,8 +347,7 @@ public class BasicSemanticChecks extends GrammarTreeVisitor {
 		boolean outerMostAlt = blk.parent.getType() == RULE;
 		Tree rule = tree.getAncestor(RULE);
 		String fileName = tree.getToken().getInputStream().getSourceName();
-		if ( !outerMostAlt || tree.getChildIndex() != alt.getChildCount()-1 ||
-			 blk.getChildCount()>1 )
+		if ( !outerMostAlt || blk.getChildCount()>1 )
 		{
 			ErrorType e = ErrorType.LEXER_COMMAND_PLACEMENT_ISSUE;
 			if ( tree.getType() == ACTION ) e = ErrorType.LEXER_ACTION_PLACEMENT_ISSUE;
diff --git a/tool/src/org/antlr/v4/semantics/SemanticPipeline.java b/tool/src/org/antlr/v4/semantics/SemanticPipeline.java
index da87b3b64..550b33a4c 100644
--- a/tool/src/org/antlr/v4/semantics/SemanticPipeline.java
+++ b/tool/src/org/antlr/v4/semantics/SemanticPipeline.java
@@ -151,7 +151,7 @@ public class SemanticPipeline {
 	void assignLexerTokenTypes(Grammar g, List<GrammarAST> tokensDefs) {
 		Grammar G = g.getOutermostGrammar(); // put in root, even if imported
 		for (GrammarAST def : tokensDefs) {
-			if ( def.getType()== ANTLRParser.ID ) G.defineTokenName(def.getText());
+			if ( def.getType()== ANTLRParser.TOKEN_REF ) G.defineTokenName(def.getText());
 		}
 
 		/* Define token types for nonfragment rules which do not include a 'type(...)'