diff --git a/compiler/src/dotty/tools/dotc/transform/TypeTestsCasts.scala b/compiler/src/dotty/tools/dotc/transform/TypeTestsCasts.scala
index 0b880afdd995..7d1740b2b581 100644
--- a/compiler/src/dotty/tools/dotc/transform/TypeTestsCasts.scala
+++ b/compiler/src/dotty/tools/dotc/transform/TypeTestsCasts.scala
@@ -243,7 +243,23 @@ object TypeTestsCasts {
             else foundClasses.exists(check)
           end checkSensical
 
-          if (expr.tpe <:< testType)
+          def hasUncheckedPrefix(tpe: Type): Boolean = tpe.stripped match
+            case tpe: TermRef =>
+              tpe.symbol.info.hasAnnotation(defn.UncheckedAnnot)
+              || hasUncheckedPrefix(tpe.prefix)
+            case tpe: TypeRef =>
+              tpe.symbol.hasAnnotation(defn.UncheckedAnnot)
+              || hasUncheckedPrefix(tpe.prefix)
+            case tpe: AndOrType =>
+              hasUncheckedPrefix(tpe.tp1) || hasUncheckedPrefix(tpe.tp2)
+            case tpe: AppliedType =>
+              hasUncheckedPrefix(tpe.tycon) || tpe.args.exists(hasUncheckedPrefix)
+            case tpe: TypeProxy =>
+              hasUncheckedPrefix(tpe.underlying)
+            case _ =>
+              false
+
+          if expr.tpe <:< testType && !hasUncheckedPrefix(expr.tpe) then
             if (expr.tpe.isNotNull) {
               if (!inMatch) report.warning(TypeTestAlwaysSucceeds(expr.tpe, testType), tree.srcPos)
               constant(expr, Literal(Constant(true)))
diff --git a/tests/neg/tuplePatDef.scala b/tests/neg/tuplePatDef.scala
new file mode 100644
index 000000000000..03aa4bcd15e7
--- /dev/null
+++ b/tests/neg/tuplePatDef.scala
@@ -0,0 +1,4 @@
+
+object Test {
+  val (x,y): (String, Int) = null // error: unreachable
+}
diff --git a/tests/pos/t2613.scala b/tests/pos/t2613.scala
index 17ebe2d7e9bf..2540ef12df7b 100644
--- a/tests/pos/t2613.scala
+++ b/tests/pos/t2613.scala
@@ -7,5 +7,5 @@ object Test {
 
   type M = MyRelation[_ <: Row, _ <: MyRelation[_, _]]
 
-  val (x,y): (String, M) = null
+  val (x,y): (String, M) = null : Any
 }
diff --git a/tests/pos/tuplePatDef.scala b/tests/pos/tuplePatDef.scala
deleted file mode 100644
index 22f8f8e7d6ed..000000000000
--- a/tests/pos/tuplePatDef.scala
+++ /dev/null
@@ -1,4 +0,0 @@
-
-object Test {
-  val (x,y): (String, Int) = null
-}
diff --git a/tests/run/i14705.scala b/tests/run/i14705.scala
new file mode 100644
index 000000000000..1ee4f6c7752b
--- /dev/null
+++ b/tests/run/i14705.scala
@@ -0,0 +1,19 @@
+trait Fruit
+case class Apple() extends Fruit
+case class Orange() extends Fruit
+
+case class Box[C](fruit: C) extends Fruit
+
+val apple = Box(fruit = Apple())
+val orange = Box(fruit = Orange())
+
+
+val result = List(apple, orange).map {
+  case appleBox: Box[Apple] @unchecked if appleBox.fruit.isInstanceOf[Apple] => //contains apple
+    "apple"
+  case _ =>
+    "orange"
+}
+
+@main def Test =
+  assert(result == List("apple", "orange"))