diff --git a/free_d_test.go b/free_d_test.go
index 4f8e134..36e974e 100644
--- a/free_d_test.go
+++ b/free_d_test.go
@@ -9,12 +9,12 @@ import (
 func TestMessageDecoding(t *testing.T) {
 	testCases := []struct {
 		description string
-		bytes       []byte
+		bytes       [29]byte
 		expected    FreeDPosition
 	}{
 		{
 			description: "simple position message",
-			bytes: []byte{0xd1, 0x01, 0x5a, 0x00, 0x00, 0x2d, 0x00, 0x00, 0xa6, 0x00, 0x00, 0x7f, 0xff, 0x40, 0x7f, 0xff, 0x80, 0x7f, 0xff,
+			bytes: [29]byte{0xd1, 0x01, 0x5a, 0x00, 0x00, 0x2d, 0x00, 0x00, 0xa6, 0x00, 0x00, 0x7f, 0xff, 0x40, 0x7f, 0xff, 0x80, 0x7f, 0xff,
 				0xc0, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x00, 0x00, 50,
 			},
 			expected: FreeDPosition{
@@ -48,15 +48,15 @@ func TestMessageDecoding(t *testing.T) {
 	}
 }
 
-func TestMessageEncoding(t *testing.T) {
+func TestGoodMessageEncoding(t *testing.T) {
 	testCases := []struct {
 		description string
-		expected    []byte
+		expected    [29]byte
 		message     FreeDPosition
 	}{
 		{
 			description: "simple position message",
-			expected: []byte{0xd1, 0x01, 0x5a, 0x00, 0x00, 0x2d, 0x00, 0x00, 0xa6, 0x00, 0x00, 0x7f, 0xff, 0x40, 0x7f, 0xff, 0x80, 0x7f, 0xff,
+			expected: [29]byte{0xd1, 0x01, 0x5a, 0x00, 0x00, 0x2d, 0x00, 0x00, 0xa6, 0x00, 0x00, 0x7f, 0xff, 0x40, 0x7f, 0xff, 0x80, 0x7f, 0xff,
 				0xc0, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x00, 0x00, 50,
 			},
 			message: FreeDPosition{
@@ -86,7 +86,7 @@ func TestMessageEncoding(t *testing.T) {
 }
 
 func BenchmarkMessageDecoding(b *testing.B) {
-	data := []byte{0xd1, 0x01, 0x5a, 0x00, 0x00, 0x2d, 0x00, 0x00, 0xa6, 0x00, 0x00, 0x7f, 0xff, 0x40, 0x7f, 0xff, 0x80, 0x7f, 0xff,
+	data := [29]byte{0xd1, 0x01, 0x5a, 0x00, 0x00, 0x2d, 0x00, 0x00, 0xa6, 0x00, 0x00, 0x7f, 0xff, 0x40, 0x7f, 0xff, 0x80, 0x7f, 0xff,
 		0xc0, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x00, 0x00, 50,
 	}
 	for b.Loop() {
@@ -110,3 +110,17 @@ func BenchmarkMessageEncoding(b *testing.B) {
 		Encode(message)
 	}
 }
+
+func FuzzMessageDecoding(f *testing.F) {
+	f.Add([]byte{0xd1, 0x01, 0x5a, 0x00, 0x00, 0x2d, 0x00, 0x00, 0xa6, 0x00, 0x00, 0x7f, 0xff, 0x40, 0x7f, 0xff, 0x80, 0x7f, 0xff,
+		0xc0, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x00, 0x00, 50,
+	})
+	f.Fuzz(func(t *testing.T, data []byte) {
+		if len(data) != 29 {
+			return
+		}
+		var dataArray [29]byte
+		copy(dataArray[:], data)
+		Decode(dataArray)
+	})
+}