diff --git a/assertjson/assertjson.go b/assertjson/assertjson.go
index 0954e18..f6a4da3 100644
--- a/assertjson/assertjson.go
+++ b/assertjson/assertjson.go
@@ -91,6 +91,7 @@ type JSONAssertFunc func(json *AssertJSON)
 
 // FileHas loads JSON from file and runs user callback for testing its nodes.
 func FileHas(t *testing.T, filename string, jsonAssert JSONAssertFunc) {
+	t.Helper()
 	data, err := ioutil.ReadFile(filename)
 	if err != nil {
 		assert.Failf(t, "failed to read file '%s': %s", filename, err.Error())
@@ -100,6 +101,7 @@ func FileHas(t *testing.T, filename string, jsonAssert JSONAssertFunc) {
 
 // Has - loads JSON from byte slice and runs user callback for testing its nodes.
 func Has(t *testing.T, data []byte, jsonAssert JSONAssertFunc) {
+	t.Helper()
 	body := &AssertJSON{t: t}
 	err := json.Unmarshal(data, &body.data)
 	if err != nil {
diff --git a/assertjson/assertjson_test.go b/assertjson/assertjson_test.go
index d6c09c8..3fcc62b 100644
--- a/assertjson/assertjson_test.go
+++ b/assertjson/assertjson_test.go
@@ -1,6 +1,10 @@
 package assertjson
 
-import "testing"
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
 
 func TestFileHas(t *testing.T) {
 	FileHas(t, "./../test/fixtures/object.json", func(json *AssertJSON) {
@@ -15,6 +19,9 @@ func TestFileHas(t *testing.T) {
 		// string assertions
 		json.Node("/stringNode").IsString()
 		json.Node("/stringNode").EqualToTheString("stringValue")
+		json.Node("/stringNode").AssertString(func(t *testing.T, value string) {
+			assert.Equal(t, "stringValue", value)
+		})
 		json.Node("/stringNode").Matches("^string.*$")
 		json.Node("/stringNode").DoesNotMatch("^notMatch$")
 		json.Node("/stringNode").Contains("string")
diff --git a/assertjson/string.go b/assertjson/string.go
index e16abfd..1682854 100644
--- a/assertjson/string.go
+++ b/assertjson/string.go
@@ -1,6 +1,10 @@
 package assertjson
 
-import "github.com/stretchr/testify/assert"
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
 
 // IsString asserts that the JSON node has a string value.
 func (node *AssertNode) IsString(msgAndArgs ...interface{}) {
@@ -63,3 +67,10 @@ func (node *AssertNode) IsStringWithLengthInRange(min int, max int, msgAndArgs .
 		assert.LessOrEqual(node.t, len(node.value.(string)), max, msgAndArgs...)
 	}
 }
+
+// AssertString assert that the JSON node has a string value and it satisfies by user function assertFunc.
+func (node *AssertNode) AssertString(assertFunc func(t *testing.T, value string)) {
+	if node.exists() && assert.IsType(node.t, "", node.value) {
+		assertFunc(node.t, node.value.(string))
+	}
+}