diff --git a/src/main/antlr4/Arc.g4 b/src/main/antlr4/Arc.g4
index ee5d836cf..cd845b362 100644
--- a/src/main/antlr4/Arc.g4
+++ b/src/main/antlr4/Arc.g4
@@ -111,6 +111,7 @@ iterator	: iter=(TScalarIter|TSimdIter|TFringeIter|TNdIter) '(' data=expr ')' #
 			| iter=(TScalarIter|TSimdIter|TFringeIter) '(' data=expr ',' start=expr ',' end=expr ',' stride=expr ')' # FourIter
 			| TNdIter '(' data=expr ',' start=expr ',' end=expr ',' stride=expr ',' shape=expr ',' strides=expr ')' # SixIter
 			| TRangeIter '(' start=expr ',' end=expr ',' stride=expr ')' # RangeIter
+      | TByKeyIter '(' data=expr ',' keyFunc=expr ')' # ByKeyIter
 			| expr # UnkownIter
 			;
 
@@ -129,4 +130,4 @@ commutativeBinop	: TPlus # SumOp
 annotations : TAt '(' entries+=annotationPair (',' entries+=annotationPair)* ')';
 annotationPair	: name=TIdentifier ':' value=TIdentifier # IdPair
 				| name=TIdentifier ':' value=literalExpr # LiteralPair
-				;
\ No newline at end of file
+				;