diff --git a/build.sbt b/build.sbt
index db91730b..ccddcb89 100644
--- a/build.sbt
+++ b/build.sbt
@@ -125,10 +125,10 @@ lazy val benchmarks = project.in(file("./modules/benchmarks"))
       "org.json4s" %% "json4s-native" % "3.6.7",
       "org.json4s" %% "json4s-jackson" % "3.6.7",
       "com.typesafe.play" %% "play-json" % "2.7.4",
-      "io.circe" %% "circe-core" % "0.12.0-M1",
-      "io.circe" %% "circe-generic" % "0.12.0-M1",
-      "io.circe" %% "circe-jawn" % "0.12.0-M1",
-      "io.circe" %% "circe-jackson29" % "0.12.0-M1",
+      "io.circe" %% "circe-core" % "0.12.0-M3",
+      "io.circe" %% "circe-generic" % "0.12.0-M3",
+      "io.circe" %% "circe-jawn" % "0.12.0-M3",
+      "io.circe" %% "circe-jackson29" % "0.12.0-M3",
 
       "org.knowm.xchart" % "xchart" % "3.5.4" exclude("de.erichseifert.vectorgraphics2d", "VectorGraphics2D") withSources()
     ),
diff --git a/modules/core/src/main/scala/tethys/readers/KeyReader.scala b/modules/core/src/main/scala/tethys/readers/KeyReader.scala
index 6c45e800..f600420b 100644
--- a/modules/core/src/main/scala/tethys/readers/KeyReader.scala
+++ b/modules/core/src/main/scala/tethys/readers/KeyReader.scala
@@ -1,11 +1,11 @@
 package tethys.readers
 
 trait KeyReader[A] {
-  def read(s: String): A
+  def read(s: String)(implicit fieldName: FieldName): A
 }
 
 object KeyReader {
   implicit lazy val stringKeyReader: KeyReader[String] = new KeyReader[String] {
-    override def read(s: String): String = s
+    override def read(s: String)(implicit fieldName: FieldName): String = s
   }
 }
diff --git a/modules/core/src/main/scala/tethys/readers/instances/MapReaders.scala b/modules/core/src/main/scala/tethys/readers/instances/MapReaders.scala
index 7856219a..6cd964c0 100644
--- a/modules/core/src/main/scala/tethys/readers/instances/MapReaders.scala
+++ b/modules/core/src/main/scala/tethys/readers/instances/MapReaders.scala
@@ -114,7 +114,8 @@ private[tethys] trait LowPriorityMapReaders extends IterableReaders {
           builder.result()
         case token if token.isFieldName =>
           val name = it.fieldName()
-          appendBuilder(it.next(), builder, keyReader.read(name))(fieldName.appendFieldName(name))
+          val nextFieldName = fieldName.appendFieldName(name)
+          appendBuilder(it.next(), builder, keyReader.read(name)(nextFieldName))(nextFieldName)
           recRead(it, builder)(fieldName)
 
         case token => ReaderError.wrongJson(s"Expect end of object or field name but '$token' found")(fieldName)
diff --git a/modules/enumeratum/src/main/scala/tethys/enumeratum/Enumeratum.scala b/modules/enumeratum/src/main/scala/tethys/enumeratum/Enumeratum.scala
index a5590148..4e3ba815 100644
--- a/modules/enumeratum/src/main/scala/tethys/enumeratum/Enumeratum.scala
+++ b/modules/enumeratum/src/main/scala/tethys/enumeratum/Enumeratum.scala
@@ -8,7 +8,6 @@ import tethys.writers.KeyWriter
 import tethys.{JsonReader, JsonWriter}
 
 object Enumeratum {
-  private val RootFieldName = FieldName()
 
   def reader[A <: EnumEntry](enum: Enum[A]): JsonReader[A] = new JsonReader[A] {
     def read(it: TokenIterator)(implicit fieldName: FieldName): A =
@@ -18,7 +17,7 @@ object Enumeratum {
   def writer[A <: EnumEntry](enum: Enum[A]): JsonWriter[A] = JsonWriter.stringWriter.contramap[A](_.entryName)
 
   def keyReader[E, A](enum: E)(fn: E => String => Option[A]): KeyReader[A] = new KeyReader[A] {
-    def read(str: String): A = decode(enum)(fn, str)(RootFieldName)
+    def read(str: String)(implicit fieldName: FieldName): A = decode(enum)(fn, str)
   }
 
   def keyWriter[A](fn: A => String): KeyWriter[A] = new KeyWriter[A] {
@@ -36,7 +35,7 @@ object Enumeratum {
       enum: ValueEnum[ValueType, EntryType]
   ): JsonWriter[EntryType] = JsonWriter[ValueType].contramap[EntryType](_.value)
 
-  private [this] def decode[E, A, V](enum: E)(fn: E => V => Option[A], value: V)(implicit fieldName: FieldName): A =
+  def decode[E, A, V](enum: E)(fn: E => V => Option[A], value: V)(implicit fieldName: FieldName): A =
     fn(enum)(value) match {
       case Some(result) => result
       case _            => ReaderError.wrongJson(s"$value is not a member of enum $enum")