diff --git a/package-lock.json b/package-lock.json
index 69951c8a6a..7c5355ceb9 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,5 +1,39 @@
 {
-  "lockfileVersion": 1,
+  "name": "cats-effect",
+  "lockfileVersion": 2,
+  "requires": true,
+  "packages": {
+    "": {
+      "devDependencies": {
+        "source-map-support": "^0.5.19"
+      }
+    },
+    "node_modules/buffer-from": {
+      "version": "1.1.2",
+      "resolved": "https://registry.npmjs.org/buffer-from/-/buffer-from-1.1.2.tgz",
+      "integrity": "sha512-E+XQCRwSbaaiChtv6k6Dwgc+bx+Bs6vuKJHHl5kox/BaKbhiXzqQOwK4cO22yElGp2OCmjwVhT3HmxgyPGnJfQ==",
+      "dev": true
+    },
+    "node_modules/source-map": {
+      "version": "0.6.1",
+      "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.6.1.tgz",
+      "integrity": "sha512-UjgapumWlbMhkBgzT7Ykc5YXUT46F0iKu8SGXq0bcwP5dz/h0Plj6enJqjz1Zbq2l5WaqYnrVbwWOWMyF3F47g==",
+      "dev": true,
+      "engines": {
+        "node": ">=0.10.0"
+      }
+    },
+    "node_modules/source-map-support": {
+      "version": "0.5.19",
+      "resolved": "https://registry.npmjs.org/source-map-support/-/source-map-support-0.5.19.tgz",
+      "integrity": "sha512-Wonm7zOCIJzBGQdB+thsPar0kYuCIzYvxZwlBa87yi/Mdjv7Tip2cyVbLj5o0cFPN4EVkuTwb3GDDyUx2DGnGw==",
+      "dev": true,
+      "dependencies": {
+        "buffer-from": "^1.0.0",
+        "source-map": "^0.6.0"
+      }
+    }
+  },
   "dependencies": {
     "buffer-from": {
       "version": "1.1.2",
diff --git a/std/shared/src/main/scala/cats/effect/std/MapRef.scala b/std/shared/src/main/scala/cats/effect/std/MapRef.scala
index 3e910ffe18..16675524db 100644
--- a/std/shared/src/main/scala/cats/effect/std/MapRef.scala
+++ b/std/shared/src/main/scala/cats/effect/std/MapRef.scala
@@ -49,14 +49,12 @@ object MapRef extends MapRefCompanionPlatform {
    * the default Constructor for MapRef. If Async is available, it will use a ConcurrentHashMap,
    * otherwise it will use a sharded immutable map.
    */
-  def apply[F[_]: Concurrent, K, V](): F[MapRef[F, K, Option[V]]] = {
-
+  def apply[F[_]: Concurrent, K, V]: F[MapRef[F, K, Option[V]]] = {
     Concurrent[F] match {
-      case a: Async[_] =>
-        implicit val async: Async[F] = a
-        ofConcurrentHashMap()
+      case s: Sync[F] =>
+        ofConcurrentHashMap()(s)
       case _ =>
-        ofShardedImmutableMap[F, K, V](Runtime.getRuntime.availableProcessors())
+        ofShardedImmutableMap[F, K, V](shardCount = Runtime.getRuntime.availableProcessors())
     }
 
   }