The value of each key-value pair is documented to be a Go string literal: <a href="https:&#x2F;&#x2F;golang.org&#x2F;pkg&#x2F;reflect&#x2F;#StructTag" rel="nofollow">https:&#x2F;&#x2F;golang.org&#x2F;pkg&#x2F;reflect&#x2F;#StructTag</a>. In fact, `strconv.Unquote` is used to convert the value into a string in the code, which agrees with the documentation. In any case, I modified the library in the OP to use a key-value pair and the struct tag `restructure:&quot;\\w+&quot;` works as expected.