diff --git a/server/message_store.go b/server/message_store.go
index fb6aefb..a9439ed 100644
--- a/server/message_store.go
+++ b/server/message_store.go
@@ -5,18 +5,21 @@ import (
 	"sync"
 )
 
+// Memory store allows messages to be stored in memory
 type MemoryStore struct {
 	mu     sync.Mutex
 	msgs   map[int]message
 	offset int
 }
 
+// New memory store initializes a new in memory store
 func NewMemoryStore() *MemoryStore {
 	return &MemoryStore{
 		msgs: make(map[int]message),
 	}
 }
 
+// Write will write the provided message to the in memory store
 func (m *MemoryStore) Write(msg message) error {
 	m.mu.Lock()
 	defer m.mu.Unlock()
@@ -28,6 +31,7 @@ func (m *MemoryStore) Write(msg message) error {
 	return nil
 }
 
+// ReadFrom will read messages from (and including) the provided offset and pass them to the provided handler
 func (m *MemoryStore) ReadFrom(offset int, handleFunc func(msg message)) error {
 	if offset < 0 || offset > m.offset {
 		return fmt.Errorf("invalid offset provided")
diff --git a/server/subscriber.go b/server/subscriber.go
index 415cb8a..288c094 100644
--- a/server/subscriber.go
+++ b/server/subscriber.go
@@ -44,6 +44,10 @@ func newSubscriber(peer *peer.Peer, topic *topic, ackDelay, ackTimeout time.Dura
 	offset := startAt
 
 	go func() {
+		if startAt < 0 {
+			return
+		}
+
 		err := topic.messageStore.ReadFrom(offset, func(msg message) {
 			s.messages <- msg
 		})