diff --git a/tool/src/org/antlr/v4/semantics/BasicSemanticChecks.java b/tool/src/org/antlr/v4/semantics/BasicSemanticChecks.java
index f87d0e980..9902c47ac 100644
--- a/tool/src/org/antlr/v4/semantics/BasicSemanticChecks.java
+++ b/tool/src/org/antlr/v4/semantics/BasicSemanticChecks.java
@@ -130,7 +130,7 @@ public class BasicSemanticChecks extends GrammarTreeVisitor {
 	public static final Set<String> legalSemPredOptions =
 		new HashSet<String>() {
 			{
-				add("msg");
+				add("fail");
 			}
 		};