TypeScript Version: 4.1.3 Search Terms: template literal types ``` type Pseudo = `&:${string}` const AmIPseudo1: Pseudo = '&:test' // Passes as expected const AmIPseudo: Pseudo = '&' // Fails as expected type PseudoDeclaration = { [key in Pseudo]: string } // No Errors const test: PseudoDeclaration = { 'someKey' : 'someValue' } ``` **Expected behavior:** `test` should not be able to pass the type-checking as its key 'someKey' is not of type `Pseudo`. **Actual behavior:** `test` passes the type-checking.