diff --git a/x/logic/predicate/block_test.go b/x/logic/predicate/block_test.go
index 24248045..9e9de15e 100644
--- a/x/logic/predicate/block_test.go
+++ b/x/logic/predicate/block_test.go
@@ -38,13 +38,13 @@ func TestBlock(t *testing.T) {
 				ctx := sdk.NewContext(stateStore, tc.header, false, log.NewNopLogger())
 
 				Convey("and a vm", func() {
-					vm := testutil.NewVMMust(ctx)
-					vm.Register1(engine.NewAtom("block_height"), BlockHeight)
-					vm.Register1(engine.NewAtom("block_time"), BlockTime)
-					testutil.CompileMust(ctx, vm, fmt.Sprintf("test :- %s.", tc.implication))
+					interpreter := testutil.NewInterpreterMust(ctx)
+					interpreter.Register1(engine.NewAtom("block_height"), BlockHeight)
+					interpreter.Register1(engine.NewAtom("block_time"), BlockTime)
+					testutil.CompileMust(ctx, interpreter, fmt.Sprintf("test :- %s.", tc.implication))
 
 					Convey("When the predicate is called", func() {
-						ok, err := vm.Arrive(engine.NewAtom("test"), []engine.Term{}, engine.Success, nil).Force(ctx)
+						ok, err := interpreter.Arrive(engine.NewAtom("test"), []engine.Term{}, engine.Success, nil).Force(ctx)
 
 						Convey("Then the result should be true and there should be no error", func() {
 							So(err, ShouldBeNil)
diff --git a/x/logic/predicate/chain_test.go b/x/logic/predicate/chain_test.go
index 1223c46e..4436d19e 100644
--- a/x/logic/predicate/chain_test.go
+++ b/x/logic/predicate/chain_test.go
@@ -33,13 +33,13 @@ func TestChainID(t *testing.T) {
 				stateStore := store.NewCommitMultiStore(db)
 				ctx := sdk.NewContext(stateStore, tc.header, false, log.NewNopLogger())
 
-				Convey("and a vm", func() {
-					vm := testutil.NewVMMust(ctx)
-					vm.Register1(engine.NewAtom("chain_id"), ChainID)
-					testutil.CompileMust(ctx, vm, fmt.Sprintf("test :- %s.", tc.implication))
+				Convey("and an interpreter", func() {
+					interpreter := testutil.NewInterpreterMust(ctx)
+					interpreter.Register1(engine.NewAtom("chain_id"), ChainID)
+					testutil.CompileMust(ctx, interpreter, fmt.Sprintf("test :- %s.", tc.implication))
 
 					Convey("When the predicate is called", func() {
-						ok, err := vm.Arrive(engine.NewAtom("test"), []engine.Term{}, engine.Success, nil).Force(ctx)
+						ok, err := interpreter.Arrive(engine.NewAtom("test"), []engine.Term{}, engine.Success, nil).Force(ctx)
 
 						Convey("Then the result should be true and there should be no error", func() {
 							So(err, ShouldBeNil)
diff --git a/x/logic/testutil/logic.go b/x/logic/testutil/logic.go
index 90cfbe4d..d8699836 100644
--- a/x/logic/testutil/logic.go
+++ b/x/logic/testutil/logic.go
@@ -3,18 +3,19 @@ package testutil
 import (
 	"context"
 
+	"github.com/ichiban/prolog"
 	"github.com/ichiban/prolog/engine"
 )
 
-// NewVMMust returns a new VM with the given context or panics if it fails.
-// The VM is configured with minimal settings to support testing.
-func NewVMMust(ctx context.Context) (vm *engine.VM) {
-	vm = &engine.VM{}
-	vm.Register3(engine.NewAtom("op"), engine.Op)
-	vm.Register3(engine.NewAtom("compare"), engine.Compare)
-	vm.Register2(engine.NewAtom("="), engine.Unify)
+// NewInterpreterMust returns a new Interpreter with the given context or panics if it fails.
+// The Interpreter is configured with minimal settings to support testing.
+func NewInterpreterMust(ctx context.Context) (interpreter *prolog.Interpreter) {
+	interpreter = &prolog.Interpreter{}
+	interpreter.Register3(engine.NewAtom("op"), engine.Op)
+	interpreter.Register3(engine.NewAtom("compare"), engine.Compare)
+	interpreter.Register2(engine.NewAtom("="), engine.Unify)
 
-	err := vm.Compile(ctx, `
+	err := interpreter.Compile(ctx, `
 						:-(op(1200, xfx, ':-')).
 						:-(op(1000, xfy, ',')).
 						:-(op(700, xfx, '==')).
@@ -30,8 +31,8 @@ func NewVMMust(ctx context.Context) (vm *engine.VM) {
 
 // CompileMust compiles the given source code and panics if it fails.
 // This is a convenience function for testing.
-func CompileMust(ctx context.Context, vm *engine.VM, s string, args ...interface{}) {
-	err := vm.Compile(ctx, s, args...)
+func CompileMust(ctx context.Context, interpreter *prolog.Interpreter, s string, args ...interface{}) {
+	err := interpreter.Compile(ctx, s, args...)
 	if err != nil {
 		panic(err)
 	}