diff --git a/appservice/appservice.go b/appservice/appservice.go
index 95b8d95c2..f608e8e76 100644
--- a/appservice/appservice.go
+++ b/appservice/appservice.go
@@ -31,7 +31,6 @@ import (
 	"github.com/matrix-org/dendrite/setup/config"
 	"github.com/matrix-org/dendrite/setup/kafka"
 	userapi "github.com/matrix-org/dendrite/userapi/api"
-	"github.com/matrix-org/gomatrixserverlib"
 	"github.com/sirupsen/logrus"
 )
 
@@ -44,10 +43,10 @@ func AddInternalRoutes(router *mux.Router, queryAPI appserviceAPI.AppServiceQuer
 // can call functions directly on the returned API or via an HTTP interface using AddInternalRoutes.
 func NewInternalAPI(
 	base *setup.BaseDendrite,
-	client *gomatrixserverlib.Client,
 	userAPI userapi.UserInternalAPI,
 	rsAPI roomserverAPI.RoomserverInternalAPI,
 ) appserviceAPI.AppServiceQueryAPI {
+	client := base.CreateAppserviceClient()
 	consumer, _ := kafka.SetupConsumerProducer(&base.Cfg.Global.Kafka)
 
 	// Create a connection to the appservice postgres DB
diff --git a/build/gobind/monolith.go b/build/gobind/monolith.go
index 58fe0d155..332d156bd 100644
--- a/build/gobind/monolith.go
+++ b/build/gobind/monolith.go
@@ -129,7 +129,7 @@ func (m *DendriteMonolith) Start() {
 		base, cache.New(), userAPI,
 	)
 
-	asAPI := appservice.NewInternalAPI(base, base.CreateClient(), userAPI, rsAPI)
+	asAPI := appservice.NewInternalAPI(base, userAPI, rsAPI)
 	rsAPI.SetAppserviceAPI(asAPI)
 
 	ygg.SetSessionFunc(func(address string) {
diff --git a/cmd/dendrite-demo-libp2p/main.go b/cmd/dendrite-demo-libp2p/main.go
index 2e8792b2d..0610ec777 100644
--- a/cmd/dendrite-demo-libp2p/main.go
+++ b/cmd/dendrite-demo-libp2p/main.go
@@ -163,7 +163,7 @@ func main() {
 	eduInputAPI := eduserver.NewInternalAPI(
 		&base.Base, cache.New(), userAPI,
 	)
-	asAPI := appservice.NewInternalAPI(&base.Base, base.Base.CreateClient(), userAPI, rsAPI)
+	asAPI := appservice.NewInternalAPI(&base.Base, userAPI, rsAPI)
 	rsAPI.SetAppserviceAPI(asAPI)
 	fsAPI := federationsender.NewInternalAPI(
 		&base.Base, federation, rsAPI, keyRing,
diff --git a/cmd/dendrite-demo-yggdrasil/main.go b/cmd/dendrite-demo-yggdrasil/main.go
index b74a74a65..2a4a335ab 100644
--- a/cmd/dendrite-demo-yggdrasil/main.go
+++ b/cmd/dendrite-demo-yggdrasil/main.go
@@ -111,7 +111,7 @@ func main() {
 		base, cache.New(), userAPI,
 	)
 
-	asAPI := appservice.NewInternalAPI(base, base.CreateClient(), userAPI, rsAPI)
+	asAPI := appservice.NewInternalAPI(base, userAPI, rsAPI)
 	rsAPI.SetAppserviceAPI(asAPI)
 	fsAPI := federationsender.NewInternalAPI(
 		base, federation, rsAPI, keyRing,
diff --git a/cmd/dendrite-monolith-server/main.go b/cmd/dendrite-monolith-server/main.go
index b8a3e231f..b82f73211 100644
--- a/cmd/dendrite-monolith-server/main.go
+++ b/cmd/dendrite-monolith-server/main.go
@@ -121,9 +121,7 @@ func main() {
 		eduInputAPI = base.EDUServerClient()
 	}
 
-	client := base.CreateClient()
-
-	asAPI := appservice.NewInternalAPI(base, client, userAPI, rsAPI)
+	asAPI := appservice.NewInternalAPI(base, userAPI, rsAPI)
 	if base.UseHTTPAPIs {
 		appservice.AddInternalRoutes(base.InternalAPIMux, asAPI)
 		asAPI = base.AppserviceHTTPClient()
@@ -133,7 +131,7 @@ func main() {
 	monolith := setup.Monolith{
 		Config:    base.Cfg,
 		AccountDB: accountDB,
-		Client:    client,
+		Client:    base.CreateClient(),
 		FedClient: federation,
 		KeyRing:   keyRing,
 
diff --git a/cmd/dendrite-polylith-multi/personalities/appservice.go b/cmd/dendrite-polylith-multi/personalities/appservice.go
index 5be3e594e..d269b15d4 100644
--- a/cmd/dendrite-polylith-multi/personalities/appservice.go
+++ b/cmd/dendrite-polylith-multi/personalities/appservice.go
@@ -23,9 +23,8 @@ import (
 func Appservice(base *setup.BaseDendrite, cfg *config.Dendrite) {
 	userAPI := base.UserAPIClient()
 	rsAPI := base.RoomserverHTTPClient()
-	client := base.CreateClient()
 
-	intAPI := appservice.NewInternalAPI(base, client, userAPI, rsAPI)
+	intAPI := appservice.NewInternalAPI(base, userAPI, rsAPI)
 	appservice.AddInternalRoutes(base.InternalAPIMux, intAPI)
 
 	base.SetupAndServeHTTP(
diff --git a/cmd/generate-config/main.go b/cmd/generate-config/main.go
index fa0da10c5..9ef0f0b41 100644
--- a/cmd/generate-config/main.go
+++ b/cmd/generate-config/main.go
@@ -61,6 +61,7 @@ func main() {
 	}
 
 	if *defaultsForCI {
+		cfg.AppServiceAPI.DisableTLSValidation = true
 		cfg.ClientAPI.RateLimiting.Enabled = false
 		cfg.FederationSender.DisableTLSValidation = true
 		cfg.MSCs.MSCs = []string{"msc2836", "msc2946", "msc2444", "msc2753"}
diff --git a/dendrite-config.yaml b/dendrite-config.yaml
index a3d1065d4..bf604c9d6 100644
--- a/dendrite-config.yaml
+++ b/dendrite-config.yaml
@@ -125,6 +125,11 @@ app_service_api:
     max_idle_conns: 2
     conn_max_lifetime: -1
 
+  # Disable the validation of TLS certificates of appservices. This is
+  # not recommended in production since it may allow appservice traffic
+  # to be sent to an unverified endpoint.
+  disable_tls_validation: false
+
   # Appservice configuration files to load into this homeserver.
   config_files: []
 
diff --git a/setup/base.go b/setup/base.go
index e9aa2a45e..9919bd42c 100644
--- a/setup/base.go
+++ b/setup/base.go
@@ -290,6 +290,20 @@ func (b *BaseDendrite) CreateClient() *gomatrixserverlib.Client {
 	return client
 }
 
+// CreateClient creates a new client (normally used for media fetch requests).
+// Should only be called once per component.
+func (b *BaseDendrite) CreateAppserviceClient() *gomatrixserverlib.Client {
+	opts := []gomatrixserverlib.ClientOption{
+		gomatrixserverlib.WithSkipVerify(b.Cfg.AppServiceAPI.DisableTLSValidation),
+	}
+	if b.Cfg.Global.DNSCache.Enabled {
+		opts = append(opts, gomatrixserverlib.WithDNSCache(b.DNSCache))
+	}
+	client := gomatrixserverlib.NewClient(opts...)
+	client.SetUserAgent(fmt.Sprintf("Dendrite/%s", internal.VersionString()))
+	return client
+}
+
 // CreateFederationClient creates a new federation client. Should only be called
 // once per component.
 func (b *BaseDendrite) CreateFederationClient() *gomatrixserverlib.FederationClient {
diff --git a/setup/config/config_appservice.go b/setup/config/config_appservice.go
index a042691db..a6f77abfe 100644
--- a/setup/config/config_appservice.go
+++ b/setup/config/config_appservice.go
@@ -33,6 +33,10 @@ type AppServiceAPI struct {
 
 	Database DatabaseOptions `yaml:"database"`
 
+	// DisableTLSValidation disables the validation of X.509 TLS certs
+	// on appservice endpoints. This is not recommended in production!
+	DisableTLSValidation bool `yaml:"disable_tls_validation"`
+
 	ConfigFiles []string `yaml:"config_files"`
 }