diff --git a/e2e/src/test/scala/ExtensionsSpec.scala b/e2e/src/test/scala/ExtensionsSpec.scala
index 0a31925ad..efde89f09 100644
--- a/e2e/src/test/scala/ExtensionsSpec.scala
+++ b/e2e/src/test/scala/ExtensionsSpec.scala
@@ -1,7 +1,11 @@
+import com.google.protobuf.descriptor.FileDescriptorProto
+import com.thesamet.proto.e2e.custom_options.CustomOptionsProto.{messageC, optName}
+import com.thesamet.proto.e2e.custom_options_use.FooMessage
 import com.thesamet.proto.e2e.extensions._
 import org.scalatest._
 import org.scalatest.flatspec.AnyFlatSpec
 import org.scalatest.matchers.must.Matchers
+import scalapb.descriptors.FileDescriptor
 
 class ExtensionsSpec extends AnyFlatSpec with Matchers with OptionValues {
   "BaseMessage.parseFrom" should "parse unknown fields" in {
@@ -17,4 +21,26 @@ class ExtensionsSpec extends AnyFlatSpec with Matchers with OptionValues {
     extended.extension(Extension.optInt) must be(Some(12))
     extended.extension(Extension.optString) must be(Some("bar"))
   }
+
+  "BaseMessage.parseFrom" should "parse extensions after full serialization cycle" in {
+    //** Serializing side **//
+    val fooFile   = FooMessage.scalaDescriptor.file
+    val serialized = com.google.protobuf.descriptor.FileDescriptorProto.toByteArray(fooFile.asProto)
+
+    //** De-serializing side **/
+    val javaFileDescriptorProto = com.google.protobuf.DescriptorProtos.FileDescriptorProto.parseFrom(serialized)
+
+    // Prior to PR #1963 the scalaFileDescriptorProto did not contain the options/extensions...
+    val javaFileDescriptor = FileDescriptorProto.fromJavaProto(javaFileDescriptorProto)
+
+    // ...and subsequently, the resulting fileDescriptor was also missing the options/extensions
+    val fileDescriptor = FileDescriptor.buildFrom(javaFileDescriptor, Nil)
+
+    val revivedFieldDescriptor = fileDescriptor.messages.find(_.name == "FooMessage").get.fields.find(_.name == "myField1").get
+
+    val messageCOption = revivedFieldDescriptor.asProto.getOptions.extension(messageC).get
+    val optNameOption = revivedFieldDescriptor.asProto.getOptions.extension(optName).get
+    messageCOption.c must be (Some("CCC"))
+    optNameOption.firstName must be ("John")
+  }
 }
diff --git a/scalapb-runtime/src/main/scalajvm/com/google/protobuf/descriptor/FieldOptions.scala b/scalapb-runtime/src/main/scalajvm/com/google/protobuf/descriptor/FieldOptions.scala
index c4d0f42ca..809b95eb1 100644
--- a/scalapb-runtime/src/main/scalajvm/com/google/protobuf/descriptor/FieldOptions.scala
+++ b/scalapb-runtime/src/main/scalajvm/com/google/protobuf/descriptor/FieldOptions.scala
@@ -358,7 +358,8 @@ object FieldOptions extends scalapb.GeneratedMessageCompanion[com.google.protobu
     editionDefaults = javaPbSource.getEditionDefaultsList.asScala.iterator.map(com.google.protobuf.descriptor.FieldOptions.EditionDefault.fromJavaProto(_)).toSeq,
     features = if (javaPbSource.hasFeatures) Some(com.google.protobuf.descriptor.FeatureSet.fromJavaProto(javaPbSource.getFeatures)) else _root_.scala.None,
     featureSupport = if (javaPbSource.hasFeatureSupport) Some(com.google.protobuf.descriptor.FieldOptions.FeatureSupport.fromJavaProto(javaPbSource.getFeatureSupport)) else _root_.scala.None,
-    uninterpretedOption = javaPbSource.getUninterpretedOptionList.asScala.iterator.map(com.google.protobuf.descriptor.UninterpretedOption.fromJavaProto(_)).toSeq
+    uninterpretedOption = javaPbSource.getUninterpretedOptionList.asScala.iterator.map(com.google.protobuf.descriptor.UninterpretedOption.fromJavaProto(_)).toSeq,
+    unknownFields = UnknownFieldSetProto.fromJavaProto(javaPbSource.getUnknownFields)
   )
   def parseFrom(`_input__`: _root_.com.google.protobuf.CodedInputStream): com.google.protobuf.descriptor.FieldOptions = {
     var __ctype: _root_.scala.Option[com.google.protobuf.descriptor.FieldOptions.CType] = _root_.scala.None
@@ -1235,4 +1236,19 @@ object FieldOptions extends scalapb.GeneratedMessageCompanion[com.google.protobu
     uninterpretedOption
   )
   // @@protoc_insertion_point(GeneratedMessageCompanion[google.protobuf.FieldOptions])
+
+  object UnknownFieldSetProto {
+    def fromJavaProto(javaUnknownFieldSet: com.google.protobuf.UnknownFieldSet): _root_.scalapb.UnknownFieldSet = {
+      javaUnknownFieldSet.asMap.asScala.foldLeft(_root_.scalapb.UnknownFieldSet.empty) {
+        case (aggregator, (key, field)) =>
+          aggregator.withField(key.toInt, new _root_.scalapb.UnknownFieldSet.Field(
+            varint = field.getVarintList.asScala.map(Long2long).toSeq,
+            fixed64 = field.getFixed64List.asScala.map(Long2long).toSeq,
+            fixed32 = field.getFixed32List.asScala.map(_.toInt).toSeq,
+            lengthDelimited = field.getLengthDelimitedList.asScala.toSeq,
+          )
+        )
+      }
+    }
+  }
 }