client.go                                                                |  4 ++--
 internal/string-limiter/string-limiter.go => internal/limiter/limiter.go | 14 ++++++++------

diff --git a/client.go b/client.go
index 1379b6929a03c8f5f983f1f279c040b43908147c..ac90b05d7304275b43c8a4eb3602de8bf1945a09 100644
--- a/client.go
+++ b/client.go
@@ -24,7 +24,7 @@ 	"github.com/anacrolix/missinggo/pubsub"
 	"github.com/anacrolix/missinggo/slices"
 	"github.com/anacrolix/missinggo/v2/pproffd"
 	"github.com/anacrolix/sync"
-	"github.com/anacrolix/torrent/internal/string-limiter"
+	"github.com/anacrolix/torrent/internal/limiter"
 	"github.com/anacrolix/torrent/tracker"
 	"github.com/anacrolix/torrent/webtorrent"
 	"github.com/davecgh/go-spew/spew"
@@ -80,7 +80,7 @@ 	numHalfOpen     int
 
 	websocketTrackers websocketTrackers
 
-	activeAnnounceLimiter string_limiter.Instance
+	activeAnnounceLimiter limiter.Instance
 }
 
 type ipStr string
diff --git a/internal/string-limiter/string-limiter.go b/internal/limiter/limiter.go
rename from internal/string-limiter/string-limiter.go
rename to internal/limiter/limiter.go
index 8a8f91dcd0588ad0d47d20ea8d1095ec1f0a30b3..1fd29db4300d16901586996ac1ce673b7c9ae907 100644
--- a/internal/string-limiter/string-limiter.go
+++ b/internal/limiter/limiter.go
@@ -1,15 +1,17 @@
-package string_limiter
+package limiter
 
 import "sync"
 
-// Manages resources with a limited number of concurrent slots for use keyed by a string.
+type Key = interface{}
+
+// Manages resources with a limited number of concurrent slots for use for each key.
 type Instance struct {
 	SlotsPerKey int
 
 	mu sync.Mutex
 	// Limits concurrent use of a resource. Push into the channel to use a slot, and receive to free
 	// up a slot.
-	active map[string]*activeValueType
+	active map[Key]*activeValueType
 }
 
 type activeValueType struct {
@@ -19,7 +21,7 @@ }
 
 type ActiveValueRef struct {
 	v *activeValueType
-	k string
+	k Key
 	i *Instance
 }
 
@@ -40,11 +42,11 @@ }
 
 // Get a reference to the values for a key. You should make sure to call Drop exactly once on the
 // returned value when done.
-func (i *Instance) GetRef(key string) ActiveValueRef {
+func (i *Instance) GetRef(key Key) ActiveValueRef {
 	i.mu.Lock()
 	defer i.mu.Unlock()
 	if i.active == nil {
-		i.active = make(map[string]*activeValueType)
+		i.active = make(map[Key]*activeValueType)
 	}
 	v, ok := i.active[key]
 	if !ok {