diff --git a/Dockerfile.run b/Dockerfile.run
index fb43123..cca51f8 100644
--- a/Dockerfile.run
+++ b/Dockerfile.run
@@ -2,10 +2,10 @@ FROM alpine
 
 RUN apk --update add ca-certificates
 
-ADD play-with-docker /bin/play-with-docker
-COPY ./www /bin/www
+ADD play-with-docker /app/play-with-docker
+COPY ./www /app/www
 
-WORKDIR /bin
-CMD ["play-with-docker"]
+WORKDIR /app
+CMD ["./play-with-docker"]
 
 EXPOSE 3000
diff --git a/handlers/new_instance.go b/handlers/new_instance.go
index 8e299da..cb95ab9 100644
--- a/handlers/new_instance.go
+++ b/handlers/new_instance.go
@@ -25,6 +25,8 @@ func NewInstance(rw http.ResponseWriter, req *http.Request) {
 	i, err := services.NewInstance(s)
 	if err != nil {
 		log.Println(err)
+		rw.WriteHeader(http.StatusInternalServerError)
+		return
 		//TODO: Set a status error
 	} else {
 		json.NewEncoder(rw).Encode(i)
diff --git a/services/instance.go b/services/instance.go
index 0bbe1c5..23c322e 100644
--- a/services/instance.go
+++ b/services/instance.go
@@ -66,6 +66,9 @@ func NewInstance(session *Session) (*Instance, error) {
 	rw.Lock()
 	err = saveSessionsToDisk()
 	rw.Unlock()
+	if err != nil {
+		return nil, err
+	}
 
 	wsServer.BroadcastTo(session.Id, "new instance", instance.Name, instance.IP, instance.Hostname)
 
diff --git a/services/session.go b/services/session.go
index 01f4d0c..a53a8f9 100644
--- a/services/session.go
+++ b/services/session.go
@@ -116,7 +116,7 @@ func GetSession(sessionId string) *Session {
 }
 
 func LoadSessionsFromDisk() error {
-	file, err := os.Open("./sessions.gob")
+	file, err := os.Open("./pwd/sessions.gob")
 	if err == nil {
 		decoder := gob.NewDecoder(file)
 		err = decoder.Decode(&sessions)
@@ -126,7 +126,7 @@ func LoadSessionsFromDisk() error {
 }
 
 func saveSessionsToDisk() error {
-	file, err := os.Create("./sessions.gob")
+	file, err := os.Create("./pwd/sessions.gob")
 	if err == nil {
 		encoder := gob.NewEncoder(file)
 		err = encoder.Encode(&sessions)