tests/cases/conformance/es6/Symbols/symbolType1.ts(1,1): error TS2358: The left-hand side of an 'instanceof' expression must be of type 'any', an object type or a type parameter. tests/cases/conformance/es6/Symbols/symbolType1.ts(2,19): error TS2359: The right-hand side of an 'instanceof' expression must be of type 'any' or of a type assignable to the 'Function' interface type. tests/cases/conformance/es6/Symbols/symbolType1.ts(4,19): error TS2359: The right-hand side of an 'instanceof' expression must be of type 'any' or of a type assignable to the 'Function' interface type. ==== tests/cases/conformance/es6/Symbols/symbolType1.ts (3 errors) ==== Symbol() instanceof Symbol; ~~~~~~~~ !!! error TS2358: The left-hand side of an 'instanceof' expression must be of type 'any', an object type or a type parameter. Symbol instanceof Symbol(); ~~~~~~~~ !!! error TS2359: The right-hand side of an 'instanceof' expression must be of type 'any' or of a type assignable to the 'Function' interface type. (Symbol() || {}) instanceof Object; // This one should be okay, it's a valid way of distinguishing types Symbol instanceof (Symbol() || {}); ~~~~~~~~~~~~~~~~ !!! error TS2359: The right-hand side of an 'instanceof' expression must be of type 'any' or of a type assignable to the 'Function' interface type.