diff --git a/src/github.com/matrix-org/go-neb/services/meetingbot/meetingbot.go b/src/github.com/matrix-org/go-neb/services/meetingbot/meetingbot.go
index ed4568e..5e13d24 100644
--- a/src/github.com/matrix-org/go-neb/services/meetingbot/meetingbot.go
+++ b/src/github.com/matrix-org/go-neb/services/meetingbot/meetingbot.go
@@ -3,7 +3,8 @@ package meetingbot
 
 import (
 	"fmt"
-    "regexp"
+	"regexp"
+	"sync"
 
 	"github.com/matrix-org/go-neb/types"
 	"github.com/matrix-org/gomatrix"
@@ -23,6 +24,8 @@ var currentUser string
 var meetingChair = ""
 var regexpAll = regexp.MustCompile(".*")
 
+var mutex sync.Mutex
+
 // Commands supported:
 //    !rollcall
 // Responds with a notice of "meeting started"
@@ -35,6 +38,9 @@ func (e *Service) Commands(cli *gomatrix.Client) []types.Command {
 		types.Command{
 			Path: []string{"rollcall"},
 			Command: func(roomID, userID string, args []string) (interface{}, error) {
+				mutex.Lock()
+				defer mutex.Unlock()
+
 				if meetingChair != "" {
 					return &gomatrix.TextMessage{"m.text", string("Meeting already in progress")}, nil
 				}
@@ -45,11 +51,14 @@ func (e *Service) Commands(cli *gomatrix.Client) []types.Command {
 		types.Command{
 			Path: []string{"present"},
 			Command: func(roomID, userID string, args []string) (interface{}, error) {
+				mutex.Lock()
+				defer mutex.Unlock()
+
 				var present = false
 				for i := 0; i < len(attendeesList); i++ {
 					if attendeesList[i] == userID {
 						present = true
-						break;
+						break
 					}
 				}
 				if !present {
@@ -61,20 +70,23 @@ func (e *Service) Commands(cli *gomatrix.Client) []types.Command {
 		types.Command{
 			Path: []string{"next"},
 			Command: func(roomID, userID string, args []string) (interface{}, error) {
+				mutex.Lock()
+				defer mutex.Unlock()
+
 				if userID != meetingChair {
 					return &gomatrix.TextMessage{"m.text", string("To avoid confusion, only the chair may progress")}, nil
 				}
 				if len(attendeesList) > 0 {
 					currentUser = attendeesList[0]
 					attendeesList = attendeesList[1:]
-                    doneAttendeesList = append(doneAttendeesList, currentUser)
+					doneAttendeesList = append(doneAttendeesList, currentUser)
 					var nextUser = "Silence!"
 					if len(attendeesList) > 0 {
 						nextUser = attendeesList[0]
 					}
 					return &gomatrix.TextMessage{"m.text", fmt.Sprintf("%s's turn, Followed by %s", currentUser, nextUser)}, nil
 				} else {
-                    meetingChair = ""
+					meetingChair = ""
 					return &gomatrix.TextMessage{"m.text", string("Meeting is over, thanks for attending!")}, nil
 				}
 			},
@@ -82,10 +94,12 @@ func (e *Service) Commands(cli *gomatrix.Client) []types.Command {
 	}
 }
 
-
 func (s *Service) Expansions(cli *gomatrix.Client) []types.Expansion {
 	return []types.Expansion{
 		types.Expansion{
+			mutex.Lock()
+			defer mutex.Unlock()
+
 			Regexp: regexpAll,
 			Expand: func(roomID, userID string, issueKeyGroups []string) interface{} {
 				if meetingChair != "" {
@@ -93,14 +107,14 @@ func (s *Service) Expansions(cli *gomatrix.Client) []types.Expansion {
 					for i := 0; i < len(doneAttendeesList); i++ {
 						if doneAttendeesList[i] == userID {
 							done = true
-							break;
+							break
 						}
 					}
 					var present = false
 					for i := 0; i < len(attendeesList); i++ {
 						if attendeesList[i] == userID {
 							present = true
-							break;
+							break
 						}
 					}
 					if !done && !present && userID != s.ServiceUserID() && userID != meetingChair {
@@ -115,6 +129,9 @@ func (s *Service) Expansions(cli *gomatrix.Client) []types.Expansion {
 
 func init() {
 	types.RegisterService(func(serviceID, serviceUserID, webhookEndpointURL string) types.Service {
+		mutex.Lock()
+		defer mutex.Unlock()
+
 		return &Service{
 			DefaultService: types.NewDefaultService(serviceID, serviceUserID, ServiceType),
 		}