diff --git a/README.md b/README.md
index 4d4d5982..7eead009 100644
--- a/README.md
+++ b/README.md
@@ -129,10 +129,12 @@ for sols.Next() {
 |                      | `nonvar(Term)`                                   |  *   | Succeeds if `Term` is not a variable.                                                                                                                                                                           | Prolog                                                                                   |
 |                      | `number(Term)`                                   |  *   | Succeeds if either `integer(Term)` or `float(Term)`.                                                                                                                                                            | Prolog                                                                                   |
 |                      | `callable(Term)`                                 |  *   | Succeeds if either `atom(Term)` or `compound(Term)`.                                                                                                                                                            | Prolog                                                                                   |
+|                      | `ground(Term)`                                   |  *   | Succeeds if `Term` is a ground term.                                                                                                                                                                            | Prolog                                                                                   |
 | Term Processing      | `functor(Term, Name, Arity)`                     |  *   | Succeeds if `Term` has a name `Name` and arity `Arity`.                                                                                                                                                         | [Go](https://pkg.go.dev/github.com/ichiban/prolog/engine#Functor)                        |
 |                      | `arg(Arg, Term, Value)`                          |  *   | Succeeds if the `Arg`-th argument of `Term` unifies with `Value`.                                                                                                                                               | [Go](https://pkg.go.dev/github.com/ichiban/prolog/engine#Arg)                            |
 |                      | `Term =.. List`                                  |  *   | Succeeds if `List` is a list of the functor and arguments of `Term`.                                                                                                                                            | [Go](https://pkg.go.dev/github.com/ichiban/prolog/engine#Univ)                           |
 |                      | `copy_term(In, Out)`                             |  *   | Creates a copy of `In` and unifies it with `Out`.                                                                                                                                                               | [Go](https://pkg.go.dev/github.com/ichiban/prolog/engine#CopyTerm)                       |
+|                      | `term_variables(Term, Vars)`                     |  *   | Succeeds if `Vars` unifies with a list of variables in `Term`.                                                                                                                                                  | Go                                                                                       |
 |                      | `compare(Order, Term1, Term2)`                   |  *   | Compares `Term` and `Term2` and unifies `Order` with either `<`, `=`, or `>`.                                                                                                                                   | [Go](https://pkg.go.dev/github.com/ichiban/prolog/engine#Compare)                        |
 |                      | `Term1 @=< Term2`                                |  *   | Either `Term1 == Term2` or `Term1 @< Term2`.                                                                                                                                                                    | Prolog                                                                                   |
 |                      | `Term1 == Term2`                                 |  *   | Equivalent to `compare(=, Term1, Term2)`.                                                                                                                                                                       | Prolog                                                                                   |