diff --git a/compiler/src/dotty/tools/dotc/core/Contexts.scala b/compiler/src/dotty/tools/dotc/core/Contexts.scala
index 9de714be8c37..5a0e03330ef2 100644
--- a/compiler/src/dotty/tools/dotc/core/Contexts.scala
+++ b/compiler/src/dotty/tools/dotc/core/Contexts.scala
@@ -402,8 +402,8 @@ object Contexts {
      *
      *  - as owner: The primary constructor of the class
      *  - as outer context: The context enclosing the class context
-     *  - as scope: type parameters, the parameter accessors, and
-     *    the context bound companions in the class context,
+     *  - as scope: type parameters, the parameter accessors,
+     *    the dummy capture parameters and the context bound companions in the class context,
      *
      *  The reasons for this peculiar choice of attributes are as follows:
      *
@@ -420,7 +420,7 @@ object Contexts {
     def superCallContext: Context =
       val locals = owner.typeParams
           ++ owner.asClass.unforcedDecls.filter: sym =>
-              sym.is(ParamAccessor) || sym.isContextBoundCompanion
+              sym.is(ParamAccessor) || sym.isContextBoundCompanion || sym.isDummyCaptureParam
       superOrThisCallContext(owner.primaryConstructor, newScopeWith(locals*))
 
     /** The context for the arguments of a this(...) constructor call.
diff --git a/compiler/src/dotty/tools/dotc/core/SymUtils.scala b/compiler/src/dotty/tools/dotc/core/SymUtils.scala
index 34908a2df6d6..f22002495bb3 100644
--- a/compiler/src/dotty/tools/dotc/core/SymUtils.scala
+++ b/compiler/src/dotty/tools/dotc/core/SymUtils.scala
@@ -91,7 +91,7 @@ class SymUtils:
       self.is(Synthetic) && self.infoOrCompleter.typeSymbol == defn.CBCompanion
 
     def isDummyCaptureParam(using Context): Boolean =
-      self.isAllOf(CaptureParam) && !(self.isClass || self.is(Method))
+      self.is(PhantomSymbol) && self.infoOrCompleter.typeSymbol != defn.CBCompanion
 
     /** Is this a case class for which a product mirror is generated?
     *  Excluded are value classes, abstract classes and case classes with more than one
diff --git a/tests/pos-custom-args/captures/i23737.scala b/tests/pos-custom-args/captures/i23737.scala
new file mode 100644
index 000000000000..3d2bb4f6791b
--- /dev/null
+++ b/tests/pos-custom-args/captures/i23737.scala
@@ -0,0 +1,14 @@
+import language.experimental.captureChecking
+
+class C
+
+trait A[T]
+
+trait B[CC^] extends A[C^{CC}] // error: CC not found
+
+trait D[CC^]:
+  val x: Object^{CC} = ???
+
+def f(c: C^) =
+  val b = new B[{c}] {}
+  val a: A[C^{c}] = b
\ No newline at end of file