diff --git a/src/github.com/matrix-org/go-neb/api.go b/src/github.com/matrix-org/go-neb/api.go
index 55a9599..c8356a0 100644
--- a/src/github.com/matrix-org/go-neb/api.go
+++ b/src/github.com/matrix-org/go-neb/api.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"database/sql"
+	"encoding/base64"
 	"encoding/json"
 	log "github.com/Sirupsen/logrus"
 	"github.com/matrix-org/go-neb/clients"
@@ -126,8 +127,19 @@ type webhookHandler struct {
 
 func (wh *webhookHandler) handle(w http.ResponseWriter, req *http.Request) {
 	segments := strings.Split(req.URL.Path, "/")
-	// last path segment is the service ID which we will pass the incoming request to
-	srvID := segments[len(segments)-1]
+	// last path segment is the service ID which we will pass the incoming request to,
+	// but we've base64d it.
+	base64srvID := segments[len(segments)-1]
+	bytesSrvID, err := base64.StdEncoding.DecodeString(base64srvID)
+	srvID := string(bytesSrvID)
+	if err != nil {
+		log.WithError(err).WithField("base64_service_id", base64srvID).Print(
+			"Not a b64 encoded string",
+		)
+		w.WriteHeader(400)
+		return
+	}
+
 	service, err := wh.db.LoadService(srvID)
 	if err != nil {
 		log.WithError(err).WithField("service_id", srvID).Print("Failed to load service")
diff --git a/src/github.com/matrix-org/go-neb/services/github/github.go b/src/github.com/matrix-org/go-neb/services/github/github.go
index 044aafa..893e869 100644
--- a/src/github.com/matrix-org/go-neb/services/github/github.go
+++ b/src/github.com/matrix-org/go-neb/services/github/github.go
@@ -221,20 +221,22 @@ func (s *githubService) PostRegister(oldService types.Service) {
 		log.Errorf("PostRegister: %s does not have a github session", s.ClientUserID)
 		return
 	}
-	old, ok := oldService.(*githubService)
-	if !ok {
-		log.Error("PostRegister: Provided old service is not of type GithubService")
-		return
-	}
+	if oldService != nil {
+		old, ok := oldService.(*githubService)
+		if !ok {
+			log.Error("PostRegister: Provided old service is not of type GithubService")
+			return
+		}
 
-	// TODO: We should be adding webhooks in Register() then removing old hooks in PostRegister()
-	//
-	// By doing both operations in PostRegister(), if some of the requests fail we can end up in
-	// an inconsistent state. It is a lot simpler and easy to reason about this way though, so
-	// for now it will do.
+		// TODO: We should be adding webhooks in Register() then removing old hooks in PostRegister()
+		//
+		// By doing both operations in PostRegister(), if some of the requests fail we can end up in
+		// an inconsistent state. It is a lot simpler and easy to reason about this way though, so
+		// for now it will do.
 
-	// remove any existing webhooks this service created on the user's behalf
-	modifyWebhooks(old, cli, true)
+		// remove any existing webhooks this service created on the user's behalf
+		modifyWebhooks(old, cli, true)
+	}
 
 	// make new webhooks according to service config
 	modifyWebhooks(s, cli, false)
diff --git a/src/github.com/matrix-org/go-neb/types/types.go b/src/github.com/matrix-org/go-neb/types/types.go
index 9b7ef28..e8b642a 100644
--- a/src/github.com/matrix-org/go-neb/types/types.go
+++ b/src/github.com/matrix-org/go-neb/types/types.go
@@ -1,6 +1,7 @@
 package types
 
 import (
+	"encoding/base64"
 	"encoding/json"
 	"errors"
 	"github.com/matrix-org/go-neb/matrix"
@@ -72,7 +73,9 @@ func CreateService(serviceID, serviceType string, serviceJSON []byte) (Service,
 	if f == nil {
 		return nil, errors.New("Unknown service type: " + serviceType)
 	}
-	webhookEndpointURL := baseURL + "services/hooks/" + serviceID
+
+	base64ServiceID := base64.StdEncoding.EncodeToString([]byte(serviceID))
+	webhookEndpointURL := baseURL + "services/hooks/" + base64ServiceID
 	service := f(serviceID, webhookEndpointURL)
 	if err := json.Unmarshal(serviceJSON, service); err != nil {
 		return nil, err