diff --git a/cmd/primetime/main.go b/cmd/primetime/main.go
new file mode 100644
index 0000000..5921b0e
--- /dev/null
+++ b/cmd/primetime/main.go
@@ -0,0 +1,52 @@
+package main
+
+import (
+	"bufio"
+	"encoding/json"
+	"log"
+	"math/big"
+	"net"
+
+	"protohackers/pkg/conn"
+)
+
+var (
+	malformedResponse = []byte("malformed\n")
+	trueResponse      = []byte(`{"method":"isPrime","prime":true}` + "\n")
+	falseResponse     = []byte(`{"method":"isPrime","prime":false}` + "\n")
+)
+
+type data struct {
+	Method string   `json:"method"`
+	Number *float64 `json:"number"`
+}
+
+func main() {
+	err := conn.StartSimple(primetime)
+	if err != nil {
+		log.Fatalln(err)
+	}
+}
+
+func primetime(c net.Conn) {
+	defer c.Close()
+	sc := bufio.NewScanner(c)
+	for sc.Scan() {
+		response := process(sc.Bytes())
+		c.Write(response)
+	}
+	if err := sc.Err(); err != nil {
+		log.Fatalln(err)
+	}
+}
+
+func process(buf []byte) []byte {
+	var in data
+	err := json.Unmarshal(buf, &in)
+	if err != nil || in.Method != "isPrime" || in.Number == nil {
+		return malformedResponse
+	} else if big.NewInt(int64(*in.Number)).ProbablyPrime(0) {
+		return trueResponse
+	}
+	return falseResponse
+}
diff --git a/cmd/smoketest/main.go b/cmd/smoketest/main.go
index 10f924b..717bb7b 100644
--- a/cmd/smoketest/main.go
+++ b/cmd/smoketest/main.go
@@ -1,40 +1,23 @@
 package main
 
 import (
-	"fmt"
 	"io"
 	"log"
 	"net"
-	"os"
-)
 
-const (
-	connPort = "3030"
-	connType = "tcp4"
+	"protohackers/pkg/conn"
 )
 
 func main() {
-	l, err := net.Listen(connType, ":"+connPort)
+	err := conn.StartSimple(smoketest)
 	if err != nil {
 		log.Fatalln(err)
-		os.Exit(1)
-	}
-	defer l.Close()
-
-	fmt.Println(fmt.Sprintf("Listening on port %s", connPort))
-
-	for {
-		conn, err := l.Accept()
-		if err != nil {
-			log.Fatalln(err)
-		}
-		go handleRequest(conn)
 	}
 }
 
-func handleRequest(conn net.Conn) {
-	defer conn.Close()
-	if _, err := io.Copy(conn, conn); err != nil {
+func smoketest(c net.Conn) {
+	defer c.Close()
+	if _, err := io.Copy(c, c); err != nil {
 		log.Fatalln(err)
 	}
 }
diff --git a/pkg/conn/conn.go b/pkg/conn/conn.go
new file mode 100644
index 0000000..9d266e9
--- /dev/null
+++ b/pkg/conn/conn.go
@@ -0,0 +1,32 @@
+package conn
+
+import (
+	"fmt"
+	"net"
+)
+
+const (
+	Port = ":3030"
+	Type = "tcp4"
+)
+
+func StartSimple(handler func(conn net.Conn)) error {
+	l, err := net.Listen(Type, Port)
+	if err != nil {
+		return err
+	}
+	defer l.Close()
+
+	fmt.Println(fmt.Sprintf("Listening on port %s", Port))
+
+	for {
+		c, err := l.Accept()
+		if err != nil {
+			return err
+		}
+		go handler(c)
+		if err != nil {
+			return err
+		}
+	}
+}