diff --git a/src/compiler/parser.ts b/src/compiler/parser.ts
index b08f75b0f5b..55d267cb53a 100644
--- a/src/compiler/parser.ts
+++ b/src/compiler/parser.ts
@@ -2615,6 +2615,7 @@ namespace ts {
         }
 
         function parseUnionOrIntersectionType(kind: SyntaxKind, parseConstituentType: () => TypeNode, operator: SyntaxKind): TypeNode {
+            parseOptional(operator);
             let type = parseConstituentType();
             if (token() === operator) {
                 const types = createNodeArray<TypeNode>([type], type.pos);