diff --git a/go.mod b/go.mod
index 3ce6605..bcefcf5 100644
--- a/go.mod
+++ b/go.mod
@@ -1,14 +1,3 @@
 module github.com/danielgtaylor/mexpr
 
 go 1.18
-
-require (
-	github.com/stretchr/testify v1.7.0
-	golang.org/x/exp v0.0.0-20230108222341-4b8118a2686a
-)
-
-require (
-	github.com/davecgh/go-spew v1.1.0 // indirect
-	github.com/pmezard/go-difflib v1.0.0 // indirect
-	gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c // indirect
-)
diff --git a/go.sum b/go.sum
index d522a88..e69de29 100644
--- a/go.sum
+++ b/go.sum
@@ -1,13 +0,0 @@
-github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
-github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
-github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
-github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
-github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
-github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
-golang.org/x/exp v0.0.0-20230108222341-4b8118a2686a h1:tlXy25amD5A7gOfbXdqCGN5k8ESEed/Ee1E5RcrYnqU=
-golang.org/x/exp v0.0.0-20230108222341-4b8118a2686a/go.mod h1:CxIveKay+FTh1D0yPZemJVgC/95VzuuOLq5Qi4xnoYc=
-gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
-gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
-gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/interpreter.go b/interpreter.go
index 03fc688..c26c5bc 100644
--- a/interpreter.go
+++ b/interpreter.go
@@ -3,8 +3,6 @@ package mexpr
 import (
 	"math"
 	"strings"
-
-	"golang.org/x/exp/maps"
 )
 
 // InterpreterOption passes configuration settings when creating a new
@@ -21,6 +19,16 @@ const (
 	UnquotedStrings
 )
 
+// mapValues returns the values of the map m.
+// The values will be in an indeterminate order.
+func mapValues[M ~map[K]V, K comparable, V any](m M) []V {
+	r := make([]V, 0, len(m))
+	for _, v := range m {
+		r = append(r, v)
+	}
+	return r
+}
+
 // checkBounds returns an error if the index is out of bounds.
 func checkBounds(ast *Node, input any, idx int) Error {
 	if v, ok := input.([]any); ok {
@@ -437,7 +445,7 @@ func (i *interpreter) run(ast *Node, value any) (any, Error) {
 			return nil, nil
 		}
 		if m, ok := resultLeft.(map[string]any); ok {
-			resultLeft = maps.Values(m)
+			resultLeft = mapValues(m)
 		}
 		if m, ok := resultLeft.(map[any]any); ok {
 			values := make([]any, 0, len(m))
diff --git a/interpreter_test.go b/interpreter_test.go
index 401646b..9d243bd 100644
--- a/interpreter_test.go
+++ b/interpreter_test.go
@@ -2,10 +2,9 @@ package mexpr
 
 import (
 	"encoding/json"
+	"reflect"
 	"strings"
 	"testing"
-
-	"github.com/stretchr/testify/assert"
 )
 
 func TestInterpreter(t *testing.T) {
@@ -224,7 +223,9 @@ func TestInterpreter(t *testing.T) {
 				if err != nil {
 					t.Fatal(err.Pretty(tc.expr))
 				}
-				assert.Equal(t, tc.output, result)
+				if !reflect.DeepEqual(tc.output, result) {
+					t.Fatalf("expected %v but found %v", tc.output, result)
+				}
 			}
 		})
 	}
@@ -283,7 +284,9 @@ func Benchmark(b *testing.B) {
 				ast, _ := Parse(bm.mexpr, input)
 				r, _ = Run(ast, input, StrictMode)
 			}
-			assert.Equal(b, bm.result, r)
+			if !reflect.DeepEqual(bm.result, r) {
+				b.Fatalf("expected %v but found %v", bm.result, r)
+			}
 		})
 
 		// b.Run(" expr-"+bm.name+"-slow", func(b *testing.B) {
@@ -299,13 +302,17 @@ func Benchmark(b *testing.B) {
 		b.Run("mexpr-"+bm.name+"-cached", func(b *testing.B) {
 			b.ReportAllocs()
 			ast, err := Parse(bm.mexpr, input)
-			assert.NoError(b, err)
+			if err != nil {
+				b.Fatal(err)
+			}
 			i := NewInterpreter(ast)
 			b.ResetTimer()
 			for n := 0; n < b.N; n++ {
 				r, _ = i.Run(input)
 			}
-			assert.Equal(b, bm.result, r)
+			if !reflect.DeepEqual(bm.result, r) {
+				b.Fatalf("expected %v but found %v", bm.result, r)
+			}
 		})
 
 		// b.Run(" expr-"+bm.name+"-cached", func(b *testing.B) {
diff --git a/typecheck.go b/typecheck.go
index a22782a..fe75a7a 100644
--- a/typecheck.go
+++ b/typecheck.go
@@ -4,8 +4,6 @@ import (
 	"fmt"
 	"sort"
 	"strings"
-
-	"golang.org/x/exp/maps"
 )
 
 type valueType string
@@ -19,6 +17,16 @@ const (
 	typeObject  valueType = "object"
 )
 
+// mapKeys returns the keys of the map m.
+// The keys will be in an indeterminate order.
+func mapKeys[M ~map[K]V, K comparable, V any](m M) []K {
+	r := make([]K, 0, len(m))
+	for k := range m {
+		r = append(r, k)
+	}
+	return r
+}
+
 type schema struct {
 	typeName   valueType
 	items      *schema
@@ -30,7 +38,7 @@ func (s *schema) String() string {
 		return fmt.Sprintf("%s[%s]", s.typeName, s.items)
 	}
 	if s.isObject() {
-		return fmt.Sprintf("%s{%v}", s.typeName, maps.Keys(s.properties))
+		return fmt.Sprintf("%s{%v}", s.typeName, mapKeys(s.properties))
 	}
 	return string(s.typeName)
 }
@@ -285,7 +293,7 @@ func (i *typeChecker) run(ast *Node, value any) (*schema, Error) {
 			return nil, err
 		}
 		if leftType.isObject() {
-			keys := maps.Keys(leftType.properties)
+			keys := mapKeys(leftType.properties)
 			sort.Strings(keys)
 			if len(keys) > 0 {
 				// Pick the first prop as the representative item type.