diff --git a/quicklens/src/main/scala-3/com/softwaremill/quicklens/package.scala b/quicklens/src/main/scala-3/com/softwaremill/quicklens/package.scala
index 0043e47..5fc30cf 100644
--- a/quicklens/src/main/scala-3/com/softwaremill/quicklens/package.scala
+++ b/quicklens/src/main/scala-3/com/softwaremill/quicklens/package.scala
@@ -133,12 +133,8 @@ package object quicklens {
   }
 
   object QuicklensFunctor {
-    given QuicklensFunctor[List] with {
-      def map[A, B](fa: List[A], f: A => B): List[B] = fa.map(f)
-    }
-
-    given QuicklensFunctor[Seq] with {
-      def map[A, B](fa: Seq[A], f: A => B): Seq[B] = fa.map(f)
+    given [S <: ([V] =>> Seq[V])]: QuicklensFunctor[S] with {
+      def map[A, B](fa: S[A], f: A => B): S[B] = fa.map(f).asInstanceOf[S[B]]
     }
 
     given QuicklensFunctor[Option] with {
@@ -163,14 +159,15 @@ package object quicklens {
   }
 
   object QuicklensIndexedFunctor {
-    given QuicklensIndexedFunctor[List, Int] with {
-      def at[A](fa: List[A], f: A => A, idx: Int): List[A] =
-        fa.updated(idx, f(fa(idx)))
-      def atOrElse[A](fa: List[A], f: A => A, idx: Int, default: => A): List[A] =
-        fa.updated(idx, f(fa.applyOrElse(idx, Function.const(default))))
-      def index[A](fa: List[A], f: A => A, idx: Int): List[A] =
-        if fa.isDefinedAt(idx) then fa.updated(idx, f(fa(idx))) else fa
+    given [S <: ([V] =>> Seq[V])]: QuicklensIndexedFunctor[S, Int] with {
+      def at[A](fa: S[A], f: A => A, idx: Int): S[A] =
+        fa.updated(idx, f(fa(idx))).asInstanceOf[S[A]]
+      def atOrElse[A](fa: S[A], f: A => A, idx: Int, default: => A): S[A] =
+        fa.updated(idx, f(fa.applyOrElse(idx, Function.const(default)))).asInstanceOf[S[A]]
+      def index[A](fa: S[A], f: A => A, idx: Int): S[A] =
+        if fa.isDefinedAt(idx) then fa.updated(idx, f(fa(idx))).asInstanceOf[S[A]] else fa
     }
+
     given [K, M <: ([V] =>> Map[K, V])]: QuicklensIndexedFunctor[M, K] with {
       def at[A](fa: M[A], f: A => A, idx: K): M[A] =
         fa.updated(idx, f(fa(idx))).asInstanceOf[M[A]]
diff --git a/quicklens/src/test/scala/com/softwaremill/quicklens/ModifyIndexedSeqIndexTest.scala b/quicklens/src/test/scala/com/softwaremill/quicklens/ModifyIndexedSeqIndexTest.scala
new file mode 100644
index 0000000..a2220c9
--- /dev/null
+++ b/quicklens/src/test/scala/com/softwaremill/quicklens/ModifyIndexedSeqIndexTest.scala
@@ -0,0 +1,27 @@
+package com.softwaremill.quicklens
+
+import com.softwaremill.quicklens.TestData._
+import org.scalatest.flatspec.AnyFlatSpec
+import org.scalatest.matchers.should.Matchers
+
+class ModifyIndexedSeqIndexTest extends AnyFlatSpec with Matchers {
+
+  it should "modify a non-nested indexed seq with case class item" in {
+    modify(is1)(_.index(2).a4.a5.name).using(duplicate) should be(l1at2dup)
+    modify(is1)(_.index(2))
+      .using(a3 => modify(a3)(_.a4.a5.name).using(duplicate)) should be(l1at2dup)
+  }
+
+  it should "modify a nested indexed seq using index" in {
+    modify(iss1)(_.index(2).index(1).name).using(duplicate) should be(ll1at2at1dup)
+  }
+
+  it should "modify a nested indexed seq using index and each" in {
+    modify(iss1)(_.index(2).each.name).using(duplicate) should be(ll1at2eachdup)
+    modify(iss1)(_.each.index(1).name).using(duplicate) should be(ll1eachat1dup)
+  }
+
+  it should "not modify if given index does not exist" in {
+    modify(is1)(_.index(10).a4.a5.name).using(duplicate) should be(l1)
+  }
+}
diff --git a/quicklens/src/test/scala/com/softwaremill/quicklens/ModifySeqIndexTest.scala b/quicklens/src/test/scala/com/softwaremill/quicklens/ModifySeqIndexTest.scala
new file mode 100644
index 0000000..fbaaeb3
--- /dev/null
+++ b/quicklens/src/test/scala/com/softwaremill/quicklens/ModifySeqIndexTest.scala
@@ -0,0 +1,27 @@
+package com.softwaremill.quicklens
+
+import com.softwaremill.quicklens.TestData._
+import org.scalatest.flatspec.AnyFlatSpec
+import org.scalatest.matchers.should.Matchers
+
+class ModifySeqIndexTest extends AnyFlatSpec with Matchers {
+
+  it should "modify a non-nested seq with case class item" in {
+    modify(s1)(_.index(2).a4.a5.name).using(duplicate) should be(l1at2dup)
+    modify(s1)(_.index(2))
+      .using(a3 => modify(a3)(_.a4.a5.name).using(duplicate)) should be(l1at2dup)
+  }
+
+  it should "modify a nested seq using index" in {
+    modify(ss1)(_.index(2).index(1).name).using(duplicate) should be(ll1at2at1dup)
+  }
+
+  it should "modify a nested seq using index and each" in {
+    modify(ss1)(_.index(2).each.name).using(duplicate) should be(ll1at2eachdup)
+    modify(ss1)(_.each.index(1).name).using(duplicate) should be(ll1eachat1dup)
+  }
+
+  it should "not modify if given index does not exist" in {
+    modify(s1)(_.index(10).a4.a5.name).using(duplicate) should be(l1)
+  }
+}
diff --git a/quicklens/src/test/scala/com/softwaremill/quicklens/TestData.scala b/quicklens/src/test/scala/com/softwaremill/quicklens/TestData.scala
index 47529ad..9ced840 100644
--- a/quicklens/src/test/scala/com/softwaremill/quicklens/TestData.scala
+++ b/quicklens/src/test/scala/com/softwaremill/quicklens/TestData.scala
@@ -63,6 +63,13 @@ object TestData {
   val ll1at2eachdup = List(List(A5("d1"), A5("d2")), List(A5("d3"), A5("d4"), A5("d5")), List(A5("d6d6"), A5("d7d7")))
   val ll1eachat1dup = List(List(A5("d1"), A5("d2d2")), List(A5("d3"), A5("d4d4"), A5("d5")), List(A5("d6"), A5("d7d7")))
 
+
+  val s1: Seq[A3] = l1
+  val ss1: Seq[Seq[A5]] = ll1
+
+  val is1 = l1.toIndexedSeq
+  val iss1 = ss1.map(_.toIndexedSeq).toIndexedSeq
+
   case class M2(m3: Map[String, A4])
 
   val m1 = Map("K1" -> A4(A5("d1")), "K2" -> A4(A5("d2")), "K3" -> A4(A5("d3")))