diff --git a/compiler/src/dotty/tools/dotc/core/Types.scala b/compiler/src/dotty/tools/dotc/core/Types.scala
index 8a0b0f12c167..aacaf33b574d 100644
--- a/compiler/src/dotty/tools/dotc/core/Types.scala
+++ b/compiler/src/dotty/tools/dotc/core/Types.scala
@@ -1038,17 +1038,15 @@ object Types {
       TypeComparer.isSameTypeWhenFrozen(this, that)
 
     /** Is this type a primitive value type which can be widened to the primitive value type `that`? */
-    def isValueSubType(that: Type)(using Context): Boolean = widen match {
+    def isValueSubType(that: Type)(using Context): Boolean = widenDealias match
       case self: TypeRef if self.symbol.isPrimitiveValueClass =>
-        that.widenExpr match {
+        that.widenExpr.dealias match
           case that: TypeRef if that.symbol.isPrimitiveValueClass =>
             defn.isValueSubClass(self.symbol, that.symbol)
           case _ =>
             false
-        }
       case _ =>
         false
-    }
 
     def relaxed_<:<(that: Type)(using Context): Boolean =
       (this <:< that) || (this isValueSubType that)
diff --git a/tasty/test/dotty/tools/tasty/TastyHeaderUnpicklerTest.scala b/tasty/test/dotty/tools/tasty/TastyHeaderUnpicklerTest.scala
index b9f2aff3f564..9f54c4b3061b 100644
--- a/tasty/test/dotty/tools/tasty/TastyHeaderUnpicklerTest.scala
+++ b/tasty/test/dotty/tools/tasty/TastyHeaderUnpicklerTest.scala
@@ -57,8 +57,8 @@ object TastyHeaderUnpicklerTest {
     buf.writeNat(exp)
     buf.writeNat(compilerBytes.length)
     buf.writeBytes(compilerBytes, compilerBytes.length)
-    buf.writeUncompressedLong(237478l)
-    buf.writeUncompressedLong(324789l)
+    buf.writeUncompressedLong(237478L)
+    buf.writeUncompressedLong(324789L)
     buf
   }
 
diff --git a/tests/pos/i12265.scala b/tests/pos/i12265.scala
new file mode 100644
index 000000000000..420d382a342b
--- /dev/null
+++ b/tests/pos/i12265.scala
@@ -0,0 +1,14 @@
+object OK {
+  def apply(n: Int ): Unit = ()
+  def apply(n: Long): Unit = ()
+  apply(3)  // ok
+  apply(3L) // ok
+}
+
+object KO {
+  type Key = Int
+  def apply(n: Key ): Unit = ()
+  def apply(n: Long): Unit = ()
+  apply(3)  // error
+  apply(3L) // ok
+}