diff --git a/config.json b/config.json
index 2a3f74b..7cb906e 100644
--- a/config.json
+++ b/config.json
@@ -1,4 +1,5 @@
 {
+  "ListenAddress": "127.0.0.1:8654",
   "Services": {
     "test": {
       "Script": "./example.sh",
diff --git a/main.go b/main.go
index 51aa47e..5b0e3cb 100644
--- a/main.go
+++ b/main.go
@@ -18,14 +18,20 @@ import (
 
 var config_filename = "/etc/gohookr.json"
 var checkSignature = true
+var config Config
 
 func main() {
 	r := mux.NewRouter()
 	r.HandleFunc("/webhooks/{service}", webhookHandler)
 
-	port := ":80"
-	if p, ok := os.LookupEnv("PORT"); ok {
-		port = fmt.Sprintf(":%v", p)
+	raw_config, err := ioutil.ReadFile(config_filename)
+	if err != nil {
+		panic(err.Error())
+	}
+	config = Config{}
+	json.Unmarshal(raw_config, &config)
+	if err := config.Validate(); err != nil {
+		panic(err.Error())
 	}
 
 	if p, ok := os.LookupEnv("CONFIG"); ok {
@@ -36,7 +42,7 @@ func main() {
 		checkSignature = p != "true"
 	}
 
-	log.Fatal(http.ListenAndServe(port, r))
+	log.Fatal(http.ListenAndServe(config.ListenAddress, r))
 }
 
 func webhookHandler(w http.ResponseWriter, r *http.Request) {
@@ -48,14 +54,6 @@ func webhookHandler(w http.ResponseWriter, r *http.Request) {
 		payload = string(p)
 	}
 
-	raw_config, err := ioutil.ReadFile(config_filename)
-	if err != nil {
-		writeResponse(w, 500, "Internal Server Error: Could not open config file")
-		return
-	}
-	config := Config{}
-	json.Unmarshal(raw_config, &config)
-
 	// check what service is specified in URL (/webhooks/{service}) and if it exists
 	service, ok := config.Services[string(mux.Vars(r)["service"])]
 	if !ok {
@@ -68,7 +66,7 @@ func webhookHandler(w http.ResponseWriter, r *http.Request) {
 	calculatedSignature := getSha256HMACSignature([]byte(service.Secret), payload)
 	fmt.Printf("signature = %v\n", signature)
 	fmt.Printf("calcuatedSignature = %v\n", signature)
-	if signature != calculatedSignature  && checkSignature{
+	if signature != calculatedSignature && checkSignature {
 		writeResponse(w, 400, "Bad Request: Signatures do not match")
 		return
 	}
@@ -103,13 +101,32 @@ func getSha256HMACSignature(secret []byte, data string) string {
 	return hex.EncodeToString(h.Sum(nil))
 }
 
+func (c Config) Validate() error {
+	if c.ListenAddress == "" {
+		return requiredFieldError{"ListenAddress", ""}
+	}
+
+	for serviceName, service := range c.Services {
+		if service.Script == "" {
+			return requiredFieldError{"Script", serviceName}
+		}
+		if service.SignatureHeader == "" {
+			return requiredFieldError{"SignatureHeader", serviceName}
+		}
+		if service.Secret == "" {
+			return requiredFieldError{"Secret", serviceName}
+		}
+	}
+
+	return nil
+}
+
 type Test struct {
-	Command string
+	Command   string
 	Arguments []string
 }
 
 type Service struct {
-	Gitea           bool
 	Script          string
 	Secret          string
 	SignatureHeader string
@@ -117,5 +134,15 @@ type Service struct {
 }
 
 type Config struct {
-	Services map[string]Service
+	ListenAddress string
+	Services      map[string]Service
+}
+
+type requiredFieldError struct {
+	fieldName   string
+	serviceName string
+}
+
+func (e requiredFieldError) Error() string {
+	return fmt.Sprintf("%v cannot be empty (%v)", e.fieldName, e.serviceName)
 }
diff --git a/readme.md b/readme.md
index 412c515..fbce155 100644
--- a/readme.md
+++ b/readme.md
@@ -1,8 +1,6 @@
 # gohookr
 
-A _really_ simple webhook receiver, which listens at `0.0.0.0:<port>/webhooks/<webhook-name>`.
-
-Default port is 80 and can be overriden by setting the environment variable `PORT`.
+A _really_ simple webhook receiver, which listens at `/webhooks/<webhook-name>`.
 
 Default config path is `/etc/gohookr.conf` and can be overriden by setting environment variable
 `CONFIG`.
@@ -46,10 +44,15 @@ real tests are run can simply be put before the tests.
 
 ## Example Config
 
+Required config keys are `ListenAddress` and `Services`.
+
+Requried keys per service are `Script`, `Secret`, `SignatureHeader`.
+
 An example config file can be found [here](./config.json) but also below:
 
 ```json
 {
+  "ListenAddress": "127.0.0.1:8654",
   "Services": {
     "test": {
       "Script": "./example.sh",