diff --git a/core/shared/src/main/scala-3/monocle/internal/IsoFields.scala b/core/shared/src/main/scala-3/monocle/internal/IsoFields.scala
index 170e51622..baab33697 100644
--- a/core/shared/src/main/scala-3/monocle/internal/IsoFields.scala
+++ b/core/shared/src/main/scala-3/monocle/internal/IsoFields.scala
@@ -1,28 +1,23 @@
 package monocle.internal
 
-import monocle.Iso
+import monocle.{Iso, PIso}
 import scala.quoted.{quotes, Expr, Quotes, Type}
 import scala.deriving.Mirror
 
 object IsoFields {
-  transparent inline def apply[S <: Product](using mirror: Mirror.ProductOf[S]): Iso[S, Tuple] =
+  transparent inline def apply[S <: Product](using mirror: Mirror.ProductOf[S]): PIso[S, S, ? <: Tuple, ? <: Tuple] =
     ${ IsoFieldsImpl.apply[S]('mirror) }
 }
 
 private[monocle] object IsoFieldsImpl {
 
-  def apply[S <: Product](mirror: Expr[Mirror.ProductOf[S]])(using Quotes, Type[S]): Expr[Iso[S, Tuple]] = {
-
-    def whitebox[A <: Tuple](e: Expr[Iso[S, A]]): Expr[Iso[S, Tuple]] =
-      e.asInstanceOf[Expr[Iso[S, Tuple]]]
-
+  def apply[S <: Product](mirror: Expr[Mirror.ProductOf[S]])(using Quotes, Type[S]): Expr[PIso[S, S, ? <: Tuple, ? <: Tuple]] =
     mirror match {
       case '{ type a <: Tuple; $m: Mirror.ProductOf[S] { type MirroredElemTypes = `a` } } =>
-        whitebox('{
+        '{
           val f: S => a = Tuple.fromProductTyped(_)(using $m)
           val g: a => S = $m.fromProduct(_)
           Iso[S, a](f)(g)
-        })
+        }
     }
-  }
 }
diff --git a/core/shared/src/main/scala-3/monocle/syntax/MacroSyntax.scala b/core/shared/src/main/scala-3/monocle/syntax/MacroSyntax.scala
index e4a8492d7..b44a819e9 100644
--- a/core/shared/src/main/scala-3/monocle/syntax/MacroSyntax.scala
+++ b/core/shared/src/main/scala-3/monocle/syntax/MacroSyntax.scala
@@ -13,7 +13,7 @@ trait MacroSyntax {
       * Case classes with 0 fields will correspond with `EmptyTuple`, 1 with `Tuple1[field type]`, 2 or more with a
       * tuple of all field types in the same order as the fields themselves.
       */
-    transparent inline def fields[S <: Product: Mirror.ProductOf]: Iso[S, Tuple] =
+    transparent inline def fields[S <: Product: Mirror.ProductOf]: PIso[S, S, ? <: Tuple, ? <: Tuple] =
       IsoFields[S]
   }