diff --git a/tool/src/main/antlr3/org/antlr/grammar/v3/CodeGenTreeWalker.g b/tool/src/main/antlr3/org/antlr/grammar/v3/CodeGenTreeWalker.g
index 9c107b531..98d77582e 100644
--- a/tool/src/main/antlr3/org/antlr/grammar/v3/CodeGenTreeWalker.g
+++ b/tool/src/main/antlr3/org/antlr/grammar/v3/CodeGenTreeWalker.g
@@ -56,6 +56,7 @@ import org.antlr.codegen.*;
 import java.util.HashSet;
 import java.util.Set;
 import java.util.Collection;
+import java.util.Collections;
 import org.antlr.runtime.BitSet;
 import org.antlr.runtime.DFA;
 import org.stringtemplate.v4.ST;
@@ -284,6 +285,8 @@ protected final List<String> getTokenTypesAsTargetLabels(Collection<GrammarAST>
         }
         labels.add( label );
     }
+    // Ensure repeatable parser builds
+    Collections.sort( labels);
     return labels;
 }
 
diff --git a/tool/src/main/java/org/antlr/tool/Grammar.java b/tool/src/main/java/org/antlr/tool/Grammar.java
index 667ebb2dd..2ecd2ea80 100644
--- a/tool/src/main/java/org/antlr/tool/Grammar.java
+++ b/tool/src/main/java/org/antlr/tool/Grammar.java
@@ -85,6 +85,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.TreeSet;
 import java.util.Vector;
 
 /** Represents a grammar in memory. */
@@ -1885,7 +1886,8 @@ public void defineRuleListLabel(String ruleName,
 	 *  Return a displayable token type name computed from the GrammarAST.
 	 */
 	public Set<String> getLabels(Set<GrammarAST> rewriteElements, int labelType) {
-		Set<String> labels = new HashSet<String>();
+		// Use a TreeSet so that parsers are generated repeatably
+		Set<String> labels = new TreeSet<>();
 		for (GrammarAST el : rewriteElements) {
 			if ( el.getType()==ANTLRParser.LABEL ) {
 				String labelName = el.getText();