diff --git a/compiler/src/dotty/tools/dotc/typer/PrepareInlineable.scala b/compiler/src/dotty/tools/dotc/typer/PrepareInlineable.scala
index 5d45d1dce714..a974df67fe1b 100644
--- a/compiler/src/dotty/tools/dotc/typer/PrepareInlineable.scala
+++ b/compiler/src/dotty/tools/dotc/typer/PrepareInlineable.scala
@@ -54,7 +54,7 @@ object PrepareInlineable {
     abstract class MakeInlineableMap(val inlineSym: Symbol) extends TreeMap with Insert {
       def accessorNameOf(name: TermName, site: Symbol)(using Context): TermName =
         val accName = InlineAccessorName(name)
-        if site.is(Trait) then accName.expandedName(site) else accName
+        if site.isExtensibleClass then accName.expandedName(site) else accName
 
       /** A definition needs an accessor if it is private, protected, or qualified private
        *  and it is not part of the tree that gets inlined. The latter test is implemented
diff --git a/tests/neg/i15323.scala b/tests/neg/i15323.scala
deleted file mode 100644
index 3d25156fbcbf..000000000000
--- a/tests/neg/i15323.scala
+++ /dev/null
@@ -1,11 +0,0 @@
-class A:
-  private var x = 0
-  inline def f1(): Int =
-    x += 1;
-    x
-
-class B extends A:
-  private var x = 0 // error
-  inline def f2(): Int =
-    x += 1
-    x
diff --git a/tests/pos/i15612.scala b/tests/pos/i15612.scala
new file mode 100644
index 000000000000..b05d847dce1e
--- /dev/null
+++ b/tests/pos/i15612.scala
@@ -0,0 +1,23 @@
+import scala.reflect.TypeTest
+
+class ForSyntax[E](using E: TypeTest[E | Any, E]):
+  extension [A](aOrE: E | A)
+    inline def flatMap[B](f: A => E | B): E | B =
+      aOrE match
+        case e: E => ???
+        case _ => ???
+
+
+class UnhappyCase[E](using E: TypeTest[E | Any, E]) extends ForSyntax[E]:
+  extension [A](aOrE: E | A)
+    inline def fold[B](inline fe: E => B, inline fa: A => B): B =
+      aOrE match
+        case e: E => ???
+        case _ => ???
+
+class A:
+  private val a = 1
+  inline def foo() = a
+class B extends A:
+  private val a = 2
+  inline def bar() = a
diff --git a/tests/run-macros/i5119.check b/tests/run-macros/i5119.check
index 25a27ca667e9..2ba1156be790 100644
--- a/tests/run-macros/i5119.check
+++ b/tests/run-macros/i5119.check
@@ -1,2 +1,2 @@
-Select(Typed(Apply(Select(New(TypeIdent("StringContextOps")), "<init>"), List(Apply(Select(Select(Select(Ident("_root_"), "scala"), "StringContext"), "apply"), List(Typed(Repeated(List(Literal(StringConstant("Hello World ")), Literal(StringConstant("!"))), Inferred()), Inferred()))))), TypeIdent("StringContextOps")), "inline$sc")
+Select(Typed(Apply(Select(New(TypeIdent("StringContextOps")), "<init>"), List(Apply(Select(Select(Select(Ident("_root_"), "scala"), "StringContext"), "apply"), List(Typed(Repeated(List(Literal(StringConstant("Hello World ")), Literal(StringConstant("!"))), Inferred()), Inferred()))))), TypeIdent("StringContextOps")), "Macro$StringContextOps$$inline$sc")
 Typed(Repeated(List(Literal(IntConstant(1))), Inferred()), Inferred())