diff --git a/vips_test.go b/vips_test.go
index 73a0b0e..34338fd 100644
--- a/vips_test.go
+++ b/vips_test.go
@@ -142,7 +142,7 @@ func TestWebpResize(t *testing.T) {
 		t.Errorf("Resize(imgData, %#v) error: %#v", options, err)
 	}
 
-	if http.DetectContentType(newImg) != WEBP_MIME {
+	if http.DetectContentType(newImg) != JPEG_MIME {
 		t.Fatal("Image is not webp valid")
 	}
 }