diff --git a/.gitignore b/.gitignore
index d855be8..165e6d2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,2 @@
 bin/
-
+triplex
diff --git a/cmd/triplex/main.go b/cmd/triplex/main.go
index 72f1c6d..7750ac4 100644
--- a/cmd/triplex/main.go
+++ b/cmd/triplex/main.go
@@ -14,6 +14,76 @@ import (
 	"git.hoiting.org/micha/triplex/serial"
 )
 
+type flags struct {
+	complete string
+	encode   string
+	decode   string
+}
+
+func parseFlags() (*flags, error) {
+	complete := flag.String("complete", "", "complete code without checksum in format LLL-NNN-LL")
+	completeShort := flag.String("c", "", "alias for --complete")
+	encode := flag.String("encode", "", "encode a value to a code")
+	encodeShort := flag.String("e", "", "alias for --encode")
+	decode := flag.String("decode", "", "decode code in format LLL-NNN-LLL")
+	decodeShort := flag.String("d", "", "alias for --decode")
+	flag.Parse()
+
+	// Resolve complete flag
+	resolvedComplete := ""
+	if *complete != "" && *completeShort != "" && *complete != *completeShort {
+		return nil, fmt.Errorf("flags --complete and -c cannot both be set with different values")
+	}
+	if *complete != "" {
+		resolvedComplete = *complete
+	} else if *completeShort != "" {
+		resolvedComplete = *completeShort
+	}
+
+	// Resolve encode flag
+	resolvedEncode := ""
+	if *encode != "" && *encodeShort != "" && *encode != *encodeShort {
+		return nil, fmt.Errorf("flags --encode and -e cannot both be set with different values")
+	}
+	if *encode != "" {
+		resolvedEncode = *encode
+	} else if *encodeShort != "" {
+		resolvedEncode = *encodeShort
+	}
+
+	// Resolve decode flag
+	resolvedDecode := ""
+	if *decode != "" && *decodeShort != "" && *decode != *decodeShort {
+		return nil, fmt.Errorf("flags --decode and -d cannot both be set with different values")
+	}
+	if *decode != "" {
+		resolvedDecode = *decode
+	} else if *decodeShort != "" {
+		resolvedDecode = *decodeShort
+	}
+
+	// Check mutual exclusivity
+	selected := 0
+	if resolvedComplete != "" {
+		selected++
+	}
+	if resolvedEncode != "" {
+		selected++
+	}
+	if resolvedDecode != "" {
+		selected++
+	}
+	if selected > 1 {
+		return nil, fmt.Errorf("flags --complete, --encode, and --decode are mutually exclusive")
+	}
+
+	return &flags{
+		complete: resolvedComplete,
+		encode:   resolvedEncode,
+		decode:   resolvedDecode,
+	}, nil
+}
+
 func alreadyUsedByClient(idx uint) bool {
 	return idx%2 == 0
 }
@@ -32,49 +102,14 @@ func myRandomIndex(max uint) (uint, error) {
 }
 
 func main() {
-	complete := flag.String("complete", "", "complete code without checksum in format LLL-NNN-LL")
-	encode := flag.String("encode", "", "encode a value to a code")
-	encodeShort := flag.String("e", "", "alias for --encode")
-	decode := flag.String("decode", "", "decode code in format LLL-NNN-LLL")
-	decodeShort := flag.String("d", "", "alias for --decode")
-	flag.Parse()
-	resolvedEncode := ""
-	if *encode != "" && *encodeShort != "" && *encode != *encodeShort {
-		fmt.Println("flags --encode and -e cannot both be set with different values")
-		os.Exit(1)
-	}
-	if *encode != "" {
-		resolvedEncode = *encode
-	} else if *encodeShort != "" {
-		resolvedEncode = *encodeShort
-	}
-	resolvedDecode := ""
-	if *decode != "" && *decodeShort != "" && *decode != *decodeShort {
-		fmt.Println("flags --decode and -d cannot both be set with different values")
-		os.Exit(1)
-	}
-	if *decode != "" {
-		resolvedDecode = *decode
-	} else if *decodeShort != "" {
-		resolvedDecode = *decodeShort
-	}
-	selected := 0
-	if *complete != "" {
-		selected++
-	}
-	if resolvedEncode != "" {
-		selected++
-	}
-	if resolvedDecode != "" {
-		selected++
-	}
-	if selected > 1 {
-		fmt.Println("flags --complete, --encode, and --decode are mutually exclusive")
+	f, err := parseFlags()
+	if err != nil {
+		fmt.Println(err)
 		os.Exit(1)
 	}
 
-	if *complete != "" {
-		full, idx, err := serial.CompleteCode(*complete)
+	if f.complete != "" {
+		full, idx, err := serial.CompleteCode(f.complete)
 		if err != nil {
 			fmt.Println("complete error:", err)
 			os.Exit(1)
@@ -82,8 +117,8 @@ func main() {
 		fmt.Println("code:", full)
 		fmt.Println("idx:", idx)
 		os.Exit(0)
-	} else if resolvedEncode != "" {
-		n, err := strconv.Atoi(resolvedEncode)
+	} else if f.encode != "" {
+		n, err := strconv.Atoi(f.encode)
 		if err != nil {
 			fmt.Println("invalid number:", err)
 			os.Exit(1)
@@ -97,8 +132,8 @@ func main() {
 		fmt.Println("code:", code)
 		fmt.Println("idx:", idx)
 		os.Exit(0)
-	} else if resolvedDecode != "" {
-		code := resolvedDecode
+	} else if f.decode != "" {
+		code := f.decode
 		idx, err := serial.Decode(code)
 		if err != nil {
 			fmt.Println("decode error:", err)
@@ -109,6 +144,7 @@ func main() {
 		os.Exit(0)
 	}
 
+	// Generate a random code
 	opts := serial.RandomCodeOptions{
 		MaxAttempts: 500,
 		IsInUse: func(idx uint) bool {