diff --git a/handler.go b/handler.go
index 8a104a5..b9a647c 100644
--- a/handler.go
+++ b/handler.go
@@ -29,7 +29,7 @@ type Handler struct {
 	playground       bool
 	rootObjectFn     RootObjectFn
 	resultCallbackFn ResultCallbackFn
-	formatErrorFn    func(err gqlerrors.FormattedError) gqlerrors.FormattedError
+	formatErrorFn    func(err error) gqlerrors.FormattedError
 }
 
 type RequestOptions struct {
@@ -144,7 +144,7 @@ func (h *Handler) ContextHandler(ctx context.Context, w http.ResponseWriter, r *
 	if formatErrorFn := h.formatErrorFn; formatErrorFn != nil && len(result.Errors) > 0 {
 		formatted := make([]gqlerrors.FormattedError, len(result.Errors))
 		for i, formattedError := range result.Errors {
-			formatted[i] = formatErrorFn(formattedError)
+			formatted[i] = formatErrorFn(formattedError.OriginalError())
 		}
 		result.Errors = formatted
 	}
@@ -203,7 +203,7 @@ type Config struct {
 	Playground       bool
 	RootObjectFn     RootObjectFn
 	ResultCallbackFn ResultCallbackFn
-	FormatErrorFn    func(err gqlerrors.FormattedError) gqlerrors.FormattedError
+	FormatErrorFn    func(err error) gqlerrors.FormattedError
 }
 
 func NewConfig() *Config {
diff --git a/handler_test.go b/handler_test.go
index 7558159..4154b1a 100644
--- a/handler_test.go
+++ b/handler_test.go
@@ -2,7 +2,6 @@ package handler_test
 
 import (
 	"encoding/json"
-	"errors"
 	"fmt"
 	"io/ioutil"
 	"net/http"
@@ -215,15 +214,15 @@ func TestHandler_BasicQuery_WithRootObjFn(t *testing.T) {
 }
 
 type customError struct {
-	error
+	message string
 }
 
 func (e customError) Error() string {
-	return e.error.Error()
+	return fmt.Sprintf("%s", e.message)
 }
 
 func TestHandler_BasicQuery_WithFormatErrorFn(t *testing.T) {
-	resolverError := customError{error: errors.New("resolver error")}
+	resolverError := customError{message: "resolver error"}
 	myNameQuery := graphql.NewObject(graphql.ObjectConfig{
 		Name: "Query",
 		Fields: graphql.Fields{
@@ -252,9 +251,6 @@ func TestHandler_BasicQuery_WithFormatErrorFn(t *testing.T) {
 			},
 		},
 		Path: []interface{}{"name"},
-		Extensions: map[string]interface{}{
-			"fromFormatFn": "FROM_FORMAT_FN",
-		},
 	}
 
 	expected := &graphql.Result{
@@ -271,22 +267,16 @@ func TestHandler_BasicQuery_WithFormatErrorFn(t *testing.T) {
 	h := handler.New(&handler.Config{
 		Schema: &myNameSchema,
 		Pretty: true,
-		FormatErrorFn: func(err gqlerrors.FormattedError) gqlerrors.FormattedError {
+		FormatErrorFn: func(err error) gqlerrors.FormattedError {
 			formatErrorFnCalled = true
-			originalError := err.OriginalError()
-			switch errType := originalError.(type) {
-			case customError:
+			var formatted gqlerrors.FormattedError
+			switch err := err.(type) {
+			case *gqlerrors.Error:
+				formatted = gqlerrors.FormatError(err)
 			default:
-				t.Fatalf("unexpected error type: %v", reflect.TypeOf(errType))
-			}
-			return gqlerrors.FormattedError{
-				Message:   err.Message,
-				Locations: err.Locations,
-				Path:      err.Path,
-				Extensions: map[string]interface{}{
-					"fromFormatFn": "FROM_FORMAT_FN",
-				},
+				t.Fatalf("unexpected error type: %v", reflect.TypeOf(err))
 			}
+			return formatted
 		},
 	})
 	result, resp := executeTest(t, h, req)