diff --git a/generator_test.go b/generator_test.go
index ee365ae..7a540c4 100644
--- a/generator_test.go
+++ b/generator_test.go
@@ -12,7 +12,7 @@ import (
 )
 
 var jsonString string
-var underTest *jsonspec.TestOutputGenerator
+var underTest generator.GoGivensOutputGenerator
 
 func init() {
 	underTest = jsonspec.NewTestOutputGenerator()
@@ -75,7 +75,7 @@ func TestTestOutputGenerator_GenerateConcurrently(testing *testing.T) {
 }
 
 func TestTestOutputGenerator_FileExtension(t *testing.T) {
-	AssertThat(t, underTest.FileExtension(), is.EqualTo("text/json"))
+	AssertThat(t, underTest.ContentType(), is.EqualTo("text/json"))
 }
 
 func TestTestOutputGenerator_Panics(t *testing.T) {
diff --git a/jsongenerator.go b/jsongenerator.go
index c7af04c..9e1b7a4 100644
--- a/jsongenerator.go
+++ b/jsongenerator.go
@@ -21,7 +21,7 @@ func NewTestOutputGenerator() *TestOutputGenerator {
 }
 
 // FileExtension for the output generated.
-func (outputGenerator *TestOutputGenerator) FileExtension() string {
+func (outputGenerator *TestOutputGenerator) ContentType() string {
 	return "text/json"
 }