diff --git a/go.mod b/go.mod
index ca03b02f1..9904eba31 100644
--- a/go.mod
+++ b/go.mod
@@ -25,7 +25,7 @@ require (
 	github.com/matrix-org/dugong v0.0.0-20210921133753-66e6b1c67e2e
 	github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91
 	github.com/matrix-org/gomatrix v0.0.0-20210324163249-be2af5ef2e16
-	github.com/matrix-org/gomatrixserverlib v0.0.0-20220614141330-dff20984ec15
+	github.com/matrix-org/gomatrixserverlib v0.0.0-20220615144844-8535862e3770
 	github.com/matrix-org/pinecone v0.0.0-20220408153826-2999ea29ed48
 	github.com/matrix-org/util v0.0.0-20200807132607-55161520e1d4
 	github.com/mattn/go-sqlite3 v1.14.13
diff --git a/go.sum b/go.sum
index 173316533..e84ab3531 100644
--- a/go.sum
+++ b/go.sum
@@ -341,8 +341,8 @@ github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91/go.mod h1
 github.com/matrix-org/gomatrix v0.0.0-20190528120928-7df988a63f26/go.mod h1:3fxX6gUjWyI/2Bt7J1OLhpCzOfO/bB3AiX0cJtEKud0=
 github.com/matrix-org/gomatrix v0.0.0-20210324163249-be2af5ef2e16 h1:ZtO5uywdd5dLDCud4r0r55eP4j9FuUNpl60Gmntcop4=
 github.com/matrix-org/gomatrix v0.0.0-20210324163249-be2af5ef2e16/go.mod h1:/gBX06Kw0exX1HrwmoBibFA98yBk/jxKpGVeyQbff+s=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20220614141330-dff20984ec15 h1:hfOBccdH5cIp8EQCbKx64XOaQ3ExDnR9P864N+qYaEo=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20220614141330-dff20984ec15/go.mod h1:jX38yp3SSLJNftBg3PXU1ayd0PCLIiDHQ4xAc9DIixk=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20220615144844-8535862e3770 h1:1czNJFGVb2K6kvpU7j9DYdmBmEe1/rDRffDj//BD3/Q=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20220615144844-8535862e3770/go.mod h1:jX38yp3SSLJNftBg3PXU1ayd0PCLIiDHQ4xAc9DIixk=
 github.com/matrix-org/pinecone v0.0.0-20220408153826-2999ea29ed48 h1:W0sjjC6yjskHX4mb0nk3p0fXAlbU5bAFUFeEtlrPASE=
 github.com/matrix-org/pinecone v0.0.0-20220408153826-2999ea29ed48/go.mod h1:ulJzsVOTssIVp1j/m5eI//4VpAGDkMt5NrRuAVX7wpc=
 github.com/matrix-org/util v0.0.0-20190711121626-527ce5ddefc7/go.mod h1:vVQlW/emklohkZnOPwD3LrZUBqdfsbiyO3p1lNV8F6U=
diff --git a/internal/caching/caches.go b/internal/caching/caches.go
index 2c5ef682e..4e0bf9662 100644
--- a/internal/caching/caches.go
+++ b/internal/caching/caches.go
@@ -36,7 +36,7 @@ type keyable interface {
 }
 
 type costable interface {
-	CacheCost() int64
+	CacheCost() int
 }
 
 type CacheSize int64
diff --git a/internal/caching/impl_ristretto.go b/internal/caching/impl_ristretto.go
index f4f71f751..b6c45009d 100644
--- a/internal/caching/impl_ristretto.go
+++ b/internal/caching/impl_ristretto.go
@@ -75,10 +75,12 @@ func NewRistrettoCache(maxCost CacheSize, enablePrometheus bool) (*Caches, error
 			Prefix: roomIDsCache,
 			MaxAge: time.Hour,
 		},
-		RoomServerEvents: &RistrettoCachePartition[int64, *gomatrixserverlib.Event]{
-			cache:  cache,
-			Prefix: roomEventsCache,
-			MaxAge: time.Hour,
+		RoomServerEvents: &RistrettoCostedCachePartition[int64, *gomatrixserverlib.Event]{
+			&RistrettoCachePartition[int64, *gomatrixserverlib.Event]{
+				cache:  cache,
+				Prefix: roomEventsCache,
+				MaxAge: time.Hour,
+			},
 		},
 		RoomInfos: &RistrettoCachePartition[string, types.RoomInfo]{
 			cache:   cache,
@@ -86,17 +88,21 @@ func NewRistrettoCache(maxCost CacheSize, enablePrometheus bool) (*Caches, error
 			Mutable: true,
 			MaxAge:  time.Hour,
 		},
-		FederationPDUs: &RistrettoCachePartition[int64, *gomatrixserverlib.HeaderedEvent]{
-			cache:   cache,
-			Prefix:  federationPDUsCache,
-			Mutable: true,
-			MaxAge:  time.Hour / 2,
+		FederationPDUs: &RistrettoCostedCachePartition[int64, *gomatrixserverlib.HeaderedEvent]{
+			&RistrettoCachePartition[int64, *gomatrixserverlib.HeaderedEvent]{
+				cache:   cache,
+				Prefix:  federationPDUsCache,
+				Mutable: true,
+				MaxAge:  time.Hour / 2,
+			},
 		},
-		FederationEDUs: &RistrettoCachePartition[int64, *gomatrixserverlib.EDU]{
-			cache:   cache,
-			Prefix:  federationEDUsCache,
-			Mutable: true,
-			MaxAge:  time.Hour / 2,
+		FederationEDUs: &RistrettoCostedCachePartition[int64, *gomatrixserverlib.EDU]{
+			&RistrettoCachePartition[int64, *gomatrixserverlib.EDU]{
+				cache:   cache,
+				Prefix:  federationEDUsCache,
+				Mutable: true,
+				MaxAge:  time.Hour / 2,
+			},
 		},
 		SpaceSummaryRooms: &RistrettoCachePartition[string, gomatrixserverlib.MSC2946SpacesResponse]{
 			cache:   cache,
@@ -120,22 +126,24 @@ type RistrettoCachePartition[K keyable, V any] struct {
 	MaxAge  time.Duration
 }
 
-func (c *RistrettoCachePartition[K, V]) Set(key K, value V) {
+func (c *RistrettoCachePartition[K, V]) setWithCost(key K, value V, cost int64) {
 	bkey := fmt.Sprintf("%c%v", c.Prefix, key)
 	if !c.Mutable {
 		if v, ok := c.cache.Get(bkey); ok && v != nil && !reflect.DeepEqual(v, value) {
 			panic(fmt.Sprintf("invalid use of immutable cache tries to change value of %v from %v to %v", key, v, value))
 		}
 	}
+	c.cache.SetWithTTL(bkey, value, cost, c.MaxAge)
+}
+
+func (c *RistrettoCachePartition[K, V]) Set(key K, value V) {
 	var cost int64
-	if cv, ok := any(value).(costable); ok {
-		cost = cv.CacheCost()
-	} else if cv, ok := any(value).(string); ok {
+	if cv, ok := any(value).(string); ok {
 		cost = int64(len(cv))
 	} else {
 		cost = int64(unsafe.Sizeof(value))
 	}
-	c.cache.SetWithTTL(bkey, value, cost, c.MaxAge)
+	c.setWithCost(key, value, cost)
 }
 
 func (c *RistrettoCachePartition[K, V]) Unset(key K) {
@@ -156,3 +164,12 @@ func (c *RistrettoCachePartition[K, V]) Get(key K) (value V, ok bool) {
 	value, ok = v.(V)
 	return
 }
+
+type RistrettoCostedCachePartition[k keyable, v costable] struct {
+	*RistrettoCachePartition[k, v]
+}
+
+func (c *RistrettoCostedCachePartition[K, V]) Set(key K, value V) {
+	cost := value.CacheCost()
+	c.setWithCost(key, value, int64(cost))
+}