diff --git a/README.md b/README.md
index 72480c3..21b53fb 100644
--- a/README.md
+++ b/README.md
@@ -20,7 +20,7 @@ import (
 
 func TestClient(t *testing.T) {
 	ctx := context.Background()
-	ts := grpcstub.NewServer(t, []string{}, "path/to/route_guide.proto")
+	ts := grpcstub.NewServer(t, "path/to/route_guide.proto")
 	t.Cleanup(func() {
 		ts.Close()
 	})
diff --git a/grpcstub.go b/grpcstub.go
index 7903f23..6c65b3b 100644
--- a/grpcstub.go
+++ b/grpcstub.go
@@ -105,47 +105,47 @@ type matchFunc func(r *Request) bool
 type handlerFunc func(r *Request) *Response
 
 // NewServer returns a new server with registered *grpc.Server
-func NewServer(t *testing.T, importPaths []string, protos ...string) *Server {
+func NewServer(t *testing.T, proto string, opts ...Option) *Server {
 	t.Helper()
-	fds, err := descriptorFromFiles(importPaths, protos...)
+	c := &config{}
+	opts = append(opts, Proto(proto))
+	for _, opt := range opts {
+		if err := opt(c); err != nil {
+			t.Fatal(err)
+		}
+	}
+	fds, err := descriptorFromFiles(c.importPaths, c.protos...)
 	if err != nil {
 		t.Error(err)
 		return nil
 	}
 	s := &Server{
-		fds:    fds,
-		server: grpc.NewServer(),
-		t:      t,
+		fds: fds,
+		t:   t,
+	}
+	if c.useTLS {
+		certificate, err := tls.X509KeyPair(c.cert, c.key)
+		if err != nil {
+			t.Fatal(err)
+		}
+		tlsc := &tls.Config{
+			Certificates: []tls.Certificate{certificate},
+		}
+		creds := credentials.NewTLS(tlsc)
+		s.tlsc = tlsc
+		s.cacert = c.cacert
+		s.server = grpc.NewServer(grpc.Creds(creds))
+	} else {
+		s.server = grpc.NewServer()
 	}
 	s.startServer()
 	return s
 }
 
 // NewTLSServer returns a new server with registered secure *grpc.Server
-func NewTLSServer(t *testing.T, cacert, cert, key []byte, importPaths []string, protos ...string) *Server {
-	t.Helper()
-	fds, err := descriptorFromFiles(importPaths, protos...)
-	if err != nil {
-		t.Error(err)
-		return nil
-	}
-	certificate, err := tls.X509KeyPair(cert, key)
-	if err != nil {
-		t.Fatal(err)
-	}
-	tlsc := &tls.Config{
-		Certificates: []tls.Certificate{certificate},
-	}
-	creds := credentials.NewTLS(tlsc)
-	s := &Server{
-		fds:    fds,
-		tlsc:   tlsc,
-		cacert: cacert,
-		server: grpc.NewServer(grpc.Creds(creds)),
-		t:      t,
-	}
-	s.startServer()
-	return s
+func NewTLSServer(t *testing.T, proto string, cacert, cert, key []byte, opts ...Option) *Server {
+	opts = append(opts, UseTLS(cacert, cert, key))
+	return NewServer(t, proto, opts...)
 }
 
 // Close shuts down *grpc.Server
diff --git a/grpcstub_test.go b/grpcstub_test.go
index 1b4030b..28afb00 100644
--- a/grpcstub_test.go
+++ b/grpcstub_test.go
@@ -21,7 +21,7 @@ import (
 
 func TestUnary(t *testing.T) {
 	ctx := context.Background()
-	ts := NewServer(t, []string{}, "testdata/route_guide.proto")
+	ts := NewServer(t, "testdata/route_guide.proto")
 	t.Cleanup(func() {
 		ts.Close()
 	})
@@ -58,7 +58,7 @@ func TestUnary(t *testing.T) {
 
 func TestServerStreaming(t *testing.T) {
 	ctx := context.Background()
-	ts := NewServer(t, []string{}, "testdata/route_guide.proto")
+	ts := NewServer(t, "testdata/route_guide.proto")
 	t.Cleanup(func() {
 		ts.Close()
 	})
@@ -115,7 +115,7 @@ func TestServerStreaming(t *testing.T) {
 
 func TestClientStreaming(t *testing.T) {
 	ctx := context.Background()
-	ts := NewServer(t, []string{}, "testdata/route_guide.proto")
+	ts := NewServer(t, "testdata/route_guide.proto")
 	t.Cleanup(func() {
 		ts.Close()
 	})
@@ -157,7 +157,7 @@ func TestClientStreaming(t *testing.T) {
 
 func TestBiStreaming(t *testing.T) {
 	ctx := context.Background()
-	ts := NewServer(t, []string{}, "testdata/route_guide.proto")
+	ts := NewServer(t, "testdata/route_guide.proto")
 	t.Cleanup(func() {
 		ts.Close()
 	})
@@ -238,7 +238,7 @@ func TestBiStreaming(t *testing.T) {
 }
 
 func TestAddr(t *testing.T) {
-	ts := NewServer(t, []string{}, "testdata/route_guide.proto")
+	ts := NewServer(t, "testdata/route_guide.proto")
 	t.Cleanup(func() {
 		ts.Close()
 	})
@@ -250,7 +250,7 @@ func TestAddr(t *testing.T) {
 
 func TestServerMatch(t *testing.T) {
 	ctx := context.Background()
-	ts := NewServer(t, []string{}, "testdata/route_guide.proto")
+	ts := NewServer(t, "testdata/route_guide.proto")
 	t.Cleanup(func() {
 		ts.Close()
 	})
@@ -274,7 +274,7 @@ func TestServerMatch(t *testing.T) {
 
 func TestMatcherMatch(t *testing.T) {
 	ctx := context.Background()
-	ts := NewServer(t, []string{}, "testdata/route_guide.proto")
+	ts := NewServer(t, "testdata/route_guide.proto")
 	t.Cleanup(func() {
 		ts.Close()
 	})
@@ -298,7 +298,7 @@ func TestMatcherMatch(t *testing.T) {
 
 func TestServerService(t *testing.T) {
 	ctx := context.Background()
-	ts := NewServer(t, []string{}, "testdata/route_guide.proto")
+	ts := NewServer(t, "testdata/route_guide.proto")
 	t.Cleanup(func() {
 		ts.Close()
 	})
@@ -320,7 +320,7 @@ func TestServerService(t *testing.T) {
 
 func TestMatcherService(t *testing.T) {
 	ctx := context.Background()
-	ts := NewServer(t, []string{}, "testdata/route_guide.proto")
+	ts := NewServer(t, "testdata/route_guide.proto")
 	t.Cleanup(func() {
 		ts.Close()
 	})
@@ -342,7 +342,7 @@ func TestMatcherService(t *testing.T) {
 
 func TestMatcherMethod(t *testing.T) {
 	ctx := context.Background()
-	ts := NewServer(t, []string{}, "testdata/route_guide.proto")
+	ts := NewServer(t, "testdata/route_guide.proto")
 	t.Cleanup(func() {
 		ts.Close()
 	})
@@ -364,7 +364,7 @@ func TestMatcherMethod(t *testing.T) {
 
 func TestHeader(t *testing.T) {
 	ctx := context.Background()
-	ts := NewServer(t, []string{}, "testdata/route_guide.proto")
+	ts := NewServer(t, "testdata/route_guide.proto")
 	t.Cleanup(func() {
 		ts.Close()
 	})
@@ -391,7 +391,7 @@ func TestHeader(t *testing.T) {
 
 func TestTrailer(t *testing.T) {
 	ctx := context.Background()
-	ts := NewServer(t, []string{}, "testdata/route_guide.proto")
+	ts := NewServer(t, "testdata/route_guide.proto")
 	t.Cleanup(func() {
 		ts.Close()
 	})
@@ -418,7 +418,7 @@ func TestTrailer(t *testing.T) {
 
 func TestResponseHeader(t *testing.T) {
 	ctx := context.Background()
-	ts := NewServer(t, []string{}, "testdata/route_guide.proto")
+	ts := NewServer(t, "testdata/route_guide.proto")
 	t.Cleanup(func() {
 		ts.Close()
 	})
@@ -438,7 +438,7 @@ func TestResponseHeader(t *testing.T) {
 
 func TestStatusUnary(t *testing.T) {
 	ctx := context.Background()
-	ts := NewServer(t, []string{}, "testdata/route_guide.proto")
+	ts := NewServer(t, "testdata/route_guide.proto")
 	t.Cleanup(func() {
 		ts.Close()
 	})
@@ -472,7 +472,7 @@ func TestStatusUnary(t *testing.T) {
 
 func TestStatusServerStreaming(t *testing.T) {
 	ctx := context.Background()
-	ts := NewServer(t, []string{}, "testdata/route_guide.proto")
+	ts := NewServer(t, "testdata/route_guide.proto")
 	t.Cleanup(func() {
 		ts.Close()
 	})
@@ -518,7 +518,7 @@ func TestStatusServerStreaming(t *testing.T) {
 
 func TestStatusClientStreaming(t *testing.T) {
 	ctx := context.Background()
-	ts := NewServer(t, []string{}, "testdata/route_guide.proto")
+	ts := NewServer(t, "testdata/route_guide.proto")
 	t.Cleanup(func() {
 		ts.Close()
 	})
@@ -566,7 +566,7 @@ func TestStatusClientStreaming(t *testing.T) {
 
 func TestStatusBiStreaming(t *testing.T) {
 	ctx := context.Background()
-	ts := NewServer(t, []string{}, "testdata/route_guide.proto")
+	ts := NewServer(t, "testdata/route_guide.proto")
 	t.Cleanup(func() {
 		ts.Close()
 	})
@@ -635,7 +635,7 @@ func TestLoadProto(t *testing.T) {
 	ctx := context.Background()
 	for _, tt := range tests {
 		t.Run(tt.proto, func(t *testing.T) {
-			ts := NewServer(t, []string{}, tt.proto)
+			ts := NewServer(t, tt.proto)
 			t.Cleanup(func() {
 				ts.Close()
 			})
@@ -676,7 +676,7 @@ func TestTLSServer(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	ts := NewTLSServer(t, cacert, cert, key, []string{}, "testdata/route_guide.proto")
+	ts := NewTLSServer(t, "testdata/route_guide.proto", cacert, cert, key)
 	t.Cleanup(func() {
 		ts.Close()
 	})
diff --git a/option.go b/option.go
new file mode 100644
index 0000000..c976bc6
--- /dev/null
+++ b/option.go
@@ -0,0 +1,41 @@
+package grpcstub
+
+type config struct {
+	protos            []string
+	importPaths       []string
+	useTLS            bool
+	cacert, cert, key []byte
+}
+
+type Option func(*config) error
+
+func Proto(proto string) Option {
+	return func(c *config) error {
+		c.protos = append(c.protos, proto)
+		return nil
+	}
+}
+
+func Protos(protos []string) Option {
+	return func(c *config) error {
+		c.protos = append(c.protos, protos...)
+		return nil
+	}
+}
+
+func ImportPaths(paths []string) Option {
+	return func(c *config) error {
+		c.importPaths = append(c.importPaths, paths...)
+		return nil
+	}
+}
+
+func UseTLS(cacert, cert, key []byte) Option {
+	return func(c *config) error {
+		c.useTLS = true
+		c.cacert = cacert
+		c.cert = cert
+		c.key = key
+		return nil
+	}
+}