diff --git a/core/shared/src/main/scala/scalapb_circe/JsonFormat.scala b/core/shared/src/main/scala/scalapb_circe/JsonFormat.scala
index ad08816..e6c1f05 100644
--- a/core/shared/src/main/scala/scalapb_circe/JsonFormat.scala
+++ b/core/shared/src/main/scala/scalapb_circe/JsonFormat.scala
@@ -278,7 +278,8 @@ class Parser(
 
             val valueMap: Map[FieldDescriptor, PValue] = (for {
               fd <- cmp.scalaDescriptor.fields
-              jsValue <- values.get(serializedName(fd)) if !jsValue.isNull
+              jsValue <- values.get(ScalapbJsonCommon.jsonName(fd)).orElse(values.get(fd.asProto.getName))
+              if !jsValue.isNull
             } yield (fd, parseValue(fd, jsValue))).toMap
 
             PMessage(valueMap)
@@ -331,6 +332,7 @@ class Parser(
 }
 
 object JsonFormat {
+
   import com.google.protobuf.wrappers
   import scalapb_json.ScalapbJsonCommon._
 
diff --git a/core/shared/src/test/scala/scalapb_circe/CodecSpec.scala b/core/shared/src/test/scala/scalapb_circe/CodecSpec.scala
index e771b6f..c540aa1 100644
--- a/core/shared/src/test/scala/scalapb_circe/CodecSpec.scala
+++ b/core/shared/src/test/scala/scalapb_circe/CodecSpec.scala
@@ -76,19 +76,6 @@ class CodecSpec extends AnyFreeSpec with Matchers {
       // Using asJson with an implicit printer includes the default value.
       g.asJson mustBe Json.obj("numberOfStrings" -> Json.fromInt(0))
     }
-
-    "decode using an implicit parser w/ non-standard settings" in {
-      implicit val parser: Parser = new Parser(preservingProtoFieldNames = true)
-
-      // Use the snake-case naming to define a Guitar Json object.
-      val j = Json.obj("number_of_strings" -> Json.fromInt(42))
-
-      // Using the regular JsonFormat parser decodes to the defaultInstance.
-      JsonFormat.fromJson[Guitar](j) mustBe Guitar.defaultInstance
-
-      // Using as[T] with an implicit parser decodes back to the original value (42).
-      j.as[Guitar] mustBe Right(Guitar(42))
-    }
   }
 
   "GeneratedEnum" - {
diff --git a/core/shared/src/test/scala/scalapb_circe/JsonFormatSpec.scala b/core/shared/src/test/scala/scalapb_circe/JsonFormatSpec.scala
index a791c87..2225f98 100644
--- a/core/shared/src/test/scala/scalapb_circe/JsonFormatSpec.scala
+++ b/core/shared/src/test/scala/scalapb_circe/JsonFormatSpec.scala
@@ -338,6 +338,11 @@ class JsonFormatSpec extends AnyFlatSpec with Matchers with OptionValues {
     new Parser().fromJsonString[MyTest]("""{"optEnum":2}""") must be(MyTest(optEnum = Some(MyEnum.V2)))
   }
 
+  "TestProto" should "parse original field names" in {
+    new Parser().fromJsonString[MyTest]("""{"opt_enum":1}""") must be(MyTest(optEnum = Some(MyEnum.V1)))
+    new Parser().fromJsonString[MyTest]("""{"opt_enum":2}""") must be(MyTest(optEnum = Some(MyEnum.V2)))
+  }
+
   "PreservedTestJson" should "be TestProto when parsed from json" in {
     new Parser(preservingProtoFieldNames = true).fromJsonString[MyTest](PreservedTestJson) must be(TestProto)
   }