diff --git a/include/mbgl/style/sources/custom_geometry_source.hpp b/include/mbgl/style/sources/custom_geometry_source.hpp
index 853526ac2dd..a0b990b44b5 100644
--- a/include/mbgl/style/sources/custom_geometry_source.hpp
+++ b/include/mbgl/style/sources/custom_geometry_source.hpp
@@ -5,12 +5,13 @@
 #include <mbgl/util/geojson.hpp>
 #include <mbgl/util/range.hpp>
 #include <mbgl/util/constants.hpp>
-#include <mbgl/actor/mailbox.hpp>
 
 namespace mbgl {
 
 class OverscaledTileID;
 class CanonicalTileID;
+template <class T>
+class Actor;
 
 namespace style {
 
@@ -43,8 +44,7 @@ class CustomGeometrySource : public Source {
     class Impl;
     const Impl& impl() const;
 private:
-    std::shared_ptr<Mailbox> mailbox;    
-    std::unique_ptr<CustomTileLoader> loader;
+    std::unique_ptr<Actor<CustomTileLoader>> loader;
 };
 
 template <>
diff --git a/src/mbgl/style/custom_tile_loader.cpp b/src/mbgl/style/custom_tile_loader.cpp
index 2fc94c9d5a9..d5bebf00862 100644
--- a/src/mbgl/style/custom_tile_loader.cpp
+++ b/src/mbgl/style/custom_tile_loader.cpp
@@ -9,7 +9,6 @@ CustomTileLoader::CustomTileLoader(const TileFunction& fetchTileFn, const TileFu
 }
 
 void CustomTileLoader::fetchTile(const OverscaledTileID& tileID, ActorRef<SetTileDataFunction> callbackRef) {
-    std::lock_guard<std::mutex> lock(dataCacheMutex);
     auto cachedTileData = dataCache.find(tileID.canonical);
     if (cachedTileData != dataCache.end()) {
         callbackRef.invoke(&SetTileDataFunction::operator(), *(cachedTileData->second));
@@ -49,14 +48,12 @@ void CustomTileLoader::removeTile(const OverscaledTileID& tileID) {
         }
     }
     if (tileCallbacks->second.size() == 0) {
-        std::lock_guard<std::mutex> lock(dataCacheMutex);
         tileCallbackMap.erase(tileCallbacks);
         dataCache.erase(tileID.canonical);
     }
 }
 
 void CustomTileLoader::setTileData(const CanonicalTileID& tileID, const GeoJSON& data) {
-    std::lock_guard<std::mutex> lock(dataCacheMutex);
 
     auto iter = tileCallbackMap.find(tileID);
     if (iter == tileCallbackMap.end()) return;
@@ -76,10 +73,7 @@ void CustomTileLoader::invalidateTile(const CanonicalTileID& tileID) {
         invokeTileCancel(tileID);
     }
     tileCallbackMap.erase(tileCallbacks);
-    {
-        std::lock_guard<std::mutex> lock(dataCacheMutex);
-        dataCache.erase(tileID);
-    }
+    dataCache.erase(tileID);
 }
 
 void CustomTileLoader::invalidateRegion(const LatLngBounds& bounds, Range<uint8_t> ) {
@@ -87,7 +81,6 @@ void CustomTileLoader::invalidateRegion(const LatLngBounds& bounds, Range<uint8_
         const LatLngBounds tileBounds(idtuple->first);
         if (tileBounds.intersects(bounds) || bounds.contains(tileBounds) || tileBounds.contains(bounds)) {
             for (auto iter = idtuple->second.begin(); iter != idtuple->second.end(); iter++) {
-                std::lock_guard<std::mutex> lock(dataCacheMutex);
                 auto actor = std::get<2>(*iter);
                 actor.invoke(&SetTileDataFunction::operator(), mapbox::geojson::feature_collection());
                 invokeTileCancel(idtuple->first);
diff --git a/src/mbgl/style/custom_tile_loader.hpp b/src/mbgl/style/custom_tile_loader.hpp
index fa3173ffc0d..149da69cfa0 100644
--- a/src/mbgl/style/custom_tile_loader.hpp
+++ b/src/mbgl/style/custom_tile_loader.hpp
@@ -7,7 +7,6 @@
 #include <mbgl/actor/actor_ref.hpp>
 
 #include <map>
-#include <mutex>
 
 namespace mbgl {
 namespace style {
@@ -39,7 +38,6 @@ class CustomTileLoader : private util::noncopyable {
     std::unordered_map<CanonicalTileID, std::vector<OverscaledIDFunctionTuple>> tileCallbackMap;
     // Keep around a cache of tile data to serve back for wrapped and over-zooomed tiles
     std::map<CanonicalTileID, std::unique_ptr<GeoJSON>> dataCache;
-    std::mutex dataCacheMutex;
 
 };
 
diff --git a/src/mbgl/style/sources/custom_geometry_source.cpp b/src/mbgl/style/sources/custom_geometry_source.cpp
index 657573b1f45..ab46843d380 100644
--- a/src/mbgl/style/sources/custom_geometry_source.cpp
+++ b/src/mbgl/style/sources/custom_geometry_source.cpp
@@ -1,9 +1,10 @@
 #include <mbgl/style/sources/custom_geometry_source.hpp>
 #include <mbgl/style/custom_tile_loader.hpp>
 #include <mbgl/style/sources/custom_geometry_source_impl.hpp>
+#include <mbgl/actor/actor.hpp>
 #include <mbgl/actor/scheduler.hpp>
 #include <mbgl/tile/tile_id.hpp>
-
+#include <mbgl/util/shared_thread_pool.hpp>
 #include <tuple>
 #include <map>
 
@@ -13,8 +14,7 @@ namespace style {
 CustomGeometrySource::CustomGeometrySource(std::string id,
                                        const CustomGeometrySource::Options options)
     : Source(makeMutable<CustomGeometrySource::Impl>(std::move(id), options)),
-    mailbox(std::make_shared<Mailbox>(*Scheduler::GetCurrent())),
-    loader(std::make_unique<CustomTileLoader>(options.fetchTileFunction, options.cancelTileFunction)) {
+    loader(std::make_unique<Actor<CustomTileLoader>>(*sharedThreadPool(), options.fetchTileFunction, options.cancelTileFunction)) {
 }
 
 CustomGeometrySource::~CustomGeometrySource() = default;
@@ -24,21 +24,21 @@ const CustomGeometrySource::Impl& CustomGeometrySource::impl() const {
 }
 
 void CustomGeometrySource::loadDescription(FileSource&) {
-    baseImpl = makeMutable<CustomGeometrySource::Impl>(impl(), ActorRef<CustomTileLoader>(*loader, mailbox));
+    baseImpl = makeMutable<CustomGeometrySource::Impl>(impl(), loader->self());
     loaded = true;
 }
 
 void CustomGeometrySource::setTileData(const CanonicalTileID& tileID,
                                      const GeoJSON& data) {
-    loader->setTileData(tileID, data);
+    loader->invoke(&CustomTileLoader::setTileData, tileID, data);
 }
 
 void CustomGeometrySource::invalidateTile(const CanonicalTileID& tileID) {
-    loader->invalidateTile(tileID);
+    loader->invoke(&CustomTileLoader::invalidateTile, tileID);
 }
 
 void CustomGeometrySource::invalidateRegion(const LatLngBounds& bounds) {
-    loader->invalidateRegion(bounds, impl().getZoomRange());
+    loader->invoke(&CustomTileLoader::invalidateRegion, bounds, impl().getZoomRange());
 }
     
 } // namespace style
diff --git a/test/style/source.test.cpp b/test/style/source.test.cpp
index 6a2122161db..eb419e80802 100644
--- a/test/style/source.test.cpp
+++ b/test/style/source.test.cpp
@@ -25,7 +25,7 @@
 #include <mbgl/util/image.hpp>
 
 #include <mbgl/util/tileset.hpp>
-#include <mbgl/util/default_thread_pool.hpp>
+#include <mbgl/util/shared_thread_pool.hpp>
 #include <mbgl/util/logging.hpp>
 #include <mbgl/util/optional.hpp>
 #include <mbgl/util/range.hpp>
@@ -552,7 +552,7 @@ TEST(Source, ImageSourceImageUpdate) {
 
 TEST(Source, CustomGeometrySourceSetTileData) {
     SourceTest test;
-
+    std::shared_ptr<ThreadPool> threadPool = sharedThreadPool();
     CustomGeometrySource source("source", CustomGeometrySource::Options());
     source.loadDescription(test.fileSource);