diff --git a/tools/src/main/scala/caliban/tools/ClientWriter.scala b/tools/src/main/scala/caliban/tools/ClientWriter.scala
index 9dbbdd1159..f7c8887760 100644
--- a/tools/src/main/scala/caliban/tools/ClientWriter.scala
+++ b/tools/src/main/scala/caliban/tools/ClientWriter.scala
@@ -297,7 +297,9 @@ object ClientWriter {
   ): String =
     s"""object ${typedef.name} {
        |  ${typedef.fields
-      .map(writeField(_, "_root_.caliban.client.Operations.RootQuery", optionalUnion = false))
+      .map(
+        writeField(_, "_root_.caliban.client.Operations.RootQuery", optionalUnion = false, optionalInterface = false)
+      )
       .mkString("\n  ")}
        |}
        |""".stripMargin
@@ -314,7 +316,9 @@ object ClientWriter {
   ): String =
     s"""object ${typedef.name} {
        |  ${typedef.fields
-      .map(writeField(_, "_root_.caliban.client.Operations.RootMutation", optionalUnion = false))
+      .map(
+        writeField(_, "_root_.caliban.client.Operations.RootMutation", optionalUnion = false, optionalInterface = false)
+      )
       .mkString("\n  ")}
        |}
        |""".stripMargin
@@ -331,7 +335,14 @@ object ClientWriter {
   ): String =
     s"""object ${typedef.name} {
        |  ${typedef.fields
-      .map(writeField(_, "_root_.caliban.client.Operations.RootSubscription", optionalUnion = false))
+      .map(
+        writeField(
+          _,
+          "_root_.caliban.client.Operations.RootSubscription",
+          optionalUnion = false,
+          optionalInterface = false
+        )
+      )
       .mkString("\n  ")}
        |}
        |""".stripMargin
@@ -352,17 +363,28 @@ object ClientWriter {
     scalarMappings: ScalarMappings
   ): String = {
 
-    val objectName: String      = safeTypeName(typedef.name)
+    val objectName: String = safeTypeName(typedef.name)
+
     val unionTypes              = typesMap.typesMap.collect { case (key, _: UnionTypeDefinition) => key }
     val optionalUnionTypeFields = typedef.fields.flatMap { field =>
       val isOptionalUnionType = unionTypes.exists(_.compareToIgnoreCase(field.ofType.toString) == 0)
-      if (isOptionalUnionType) Some(collectFieldInfo(field, objectName, optionalUnion = true))
+      if (isOptionalUnionType)
+        Some(collectFieldInfo(field, objectName, optionalUnion = true, optionalInterface = false))
       else None
     }
-    val fields                  = typedef.fields.map(collectFieldInfo(_, objectName, optionalUnion = false))
-    val view                    = if (genView) "\n  " + writeView(typedef.name, fields.map(_.typeInfo)) else ""
 
-    val allFields = fields ++ optionalUnionTypeFields
+    val interfaceTypes              = typesMap.typesMap.collect { case (key, _: InterfaceTypeDefinition) => key }
+    val optionalInterfaceTypeFields = typedef.fields.flatMap { field =>
+      val isOptionalInterfaceType = interfaceTypes.exists(_.compareToIgnoreCase(field.ofType.toString) == 0)
+      if (isOptionalInterfaceType)
+        Some(collectFieldInfo(field, objectName, optionalUnion = false, optionalInterface = true))
+      else None
+    }
+
+    val fields = typedef.fields.map(collectFieldInfo(_, objectName, optionalUnion = false, optionalInterface = false))
+    val view   = if (genView) "\n  " + writeView(typedef.name, fields.map(_.typeInfo)) else ""
+
+    val allFields = fields ++ optionalUnionTypeFields ++ optionalInterfaceTypeFields
 
     s"""object $objectName {$view
        |  ${allFields.map(writeFieldInfo).mkString("\n  ")}
@@ -612,12 +634,12 @@ object ClientWriter {
   private val tripleQuotes = "\"\"\""
   private val doubleQuotes = "\""
 
-  def writeField(field: FieldDefinition, typeName: String, optionalUnion: Boolean)(implicit
+  def writeField(field: FieldDefinition, typeName: String, optionalUnion: Boolean, optionalInterface: Boolean)(implicit
     typesMap: TypesMap,
     mappingClashedTypeNames: MappingClashedTypeNames,
     scalarMappings: ScalarMappings
   ): String =
-    writeFieldInfo(collectFieldInfo(field, typeName, optionalUnion))
+    writeFieldInfo(collectFieldInfo(field, typeName, optionalUnion, optionalInterface))
 
   def writeFieldInfo(fieldInfo: FieldInfo): String = {
     val FieldInfo(
@@ -640,7 +662,8 @@ object ClientWriter {
     s"""$description${deprecated}def $safeName$typeParam$args$innerSelection$implicits: SelectionBuilder[$typeName, $outputType] = _root_.caliban.client.SelectionBuilder.Field("$name", $builder$argBuilder)"""
   }
 
-  def collectFieldInfo(field: FieldDefinition, typeName: String, optionalUnion: Boolean)(implicit
+  def collectFieldInfo(field: FieldDefinition, typeName: String, optionalUnion: Boolean, optionalInterface: Boolean)(
+    implicit
     typesMap: TypesMap,
     mappingClashedTypeNames: MappingClashedTypeNames,
     scalarMappings: ScalarMappings
@@ -723,15 +746,27 @@ object ClientWriter {
           )
         }
       } else if (interfaceTypes.nonEmpty) {
-        (
-          s"[$typeLetter]",
-          s"(${interfaceTypes.map(t => s"""on${t.name}: Option[SelectionBuilder[${safeTypeName(t.name)}, $typeLetter]] = None""").mkString(", ")})",
-          writeType(field.ofType).replace(fieldType, typeLetter),
-          writeTypeBuilder(
-            field.ofType,
-            s"ChoiceOf(Map(${interfaceTypes.map(t => s""""${t.name}" -> on${t.name}""").mkString(", ")}).collect { case (k, Some(v)) => k -> Obj(v)})"
+        if (optionalInterface) {
+          (
+            s"[$typeLetter]",
+            s"(${interfaceTypes.map(t => s"""on${t.name}: Option[SelectionBuilder[${safeTypeName(t.name)}, $typeLetter]] = None""").mkString(", ")})",
+            s"Option[${writeType(field.ofType).replace(fieldType, typeLetter)}]",
+            writeTypeBuilder(
+              field.ofType,
+              s"ChoiceOf(Map(${interfaceTypes.map(t => s""""${t.name}" -> on${t.name}.fold[FieldBuilder[Option[A]]](NullField)(a => OptionOf(Obj(a)))""").mkString(", ")}))"
+            )
           )
-        )
+        } else {
+          (
+            s"[$typeLetter]",
+            s"(${interfaceTypes.map(t => s"""on${t.name}: SelectionBuilder[${safeTypeName(t.name)}, $typeLetter]""").mkString(", ")})",
+            writeType(field.ofType).replace(fieldType, typeLetter),
+            writeTypeBuilder(
+              field.ofType,
+              s"ChoiceOf(Map(${interfaceTypes.map(t => s""""${t.name}" -> Obj(on${t.name})""").mkString(", ")}))"
+            )
+          )
+        }
       } else {
         (
           s"[$typeLetter]",
@@ -759,7 +794,10 @@ object ClientWriter {
         }.mkString(", ")})"
     }
 
-    val name          = if (optionalUnion && unionTypes.nonEmpty) safeName(field.name + "Option") else safeName(field.name)
+    val name          =
+      if ((optionalUnion && unionTypes.nonEmpty) || (optionalInterface && interfaceTypes.nonEmpty))
+        safeName(field.name + "Option")
+      else safeName(field.name)
     val owner         = if (typeParam.nonEmpty) Some(fieldType) else None
     val fieldTypeInfo = FieldTypeInfo(
       field.name,
diff --git a/tools/src/test/scala/caliban/tools/ClientWriterSpec.scala b/tools/src/test/scala/caliban/tools/ClientWriterSpec.scala
index 57dc40b423..615386612f 100644
--- a/tools/src/test/scala/caliban/tools/ClientWriterSpec.scala
+++ b/tools/src/test/scala/caliban/tools/ClientWriterSpec.scala
@@ -843,6 +843,51 @@ object Client {
             )
           )
         )
+      },
+      testM("interface") {
+        val schema =
+          """
+             interface Order {
+               name: String!
+             }
+             type Ascending implements Order {
+               name: String!
+             }
+             type Sort {
+               order: Order
+             }
+            """.stripMargin
+
+        assertM(gen(schema, Map.empty, List.empty)) {
+          equalTo(
+            """import caliban.client.FieldBuilder._
+import caliban.client._
+
+object Client {
+
+  type Ascending
+  object Ascending {
+    def name: SelectionBuilder[Ascending, String] = _root_.caliban.client.SelectionBuilder.Field("name", Scalar())
+  }
+
+  type Sort
+  object Sort {
+    def order[A](onAscending: SelectionBuilder[Ascending, A]): SelectionBuilder[Sort, Option[A]] =
+      _root_.caliban.client.SelectionBuilder.Field("order", OptionOf(ChoiceOf(Map("Ascending" -> Obj(onAscending)))))
+    def orderOption[A](
+      onAscending: Option[SelectionBuilder[Ascending, A]] = None
+    ): SelectionBuilder[Sort, Option[Option[A]]] = _root_.caliban.client.SelectionBuilder.Field(
+      "order",
+      OptionOf(
+        ChoiceOf(Map("Ascending" -> onAscending.fold[FieldBuilder[Option[A]]](NullField)(a => OptionOf(Obj(a)))))
+      )
+    )
+  }
+
+}
+"""
+          )
+        }
       }
     ) @@ TestAspect.sequential
 }