diff --git a/compiler/src/dotty/tools/backend/jvm/BTypesFromSymbols.scala b/compiler/src/dotty/tools/backend/jvm/BTypesFromSymbols.scala
index b8d7ee04c870..97934935f352 100644
--- a/compiler/src/dotty/tools/backend/jvm/BTypesFromSymbols.scala
+++ b/compiler/src/dotty/tools/backend/jvm/BTypesFromSymbols.scala
@@ -113,11 +113,12 @@ class BTypesFromSymbols[I <: DottyBackendInterface](val int: I, val frontendAcce
       val directlyInheritedTraits = sym.directlyInheritedTraits
       val directlyInheritedTraitsSet = directlyInheritedTraits.toSet
       val allBaseClasses = directlyInheritedTraits.iterator.flatMap(_.asClass.baseClasses.drop(1)).toSet
-      val superCalls = superCallsMap.getOrElse(sym, Set.empty)
-      val additional = (superCalls -- directlyInheritedTraitsSet).filter(_.is(Trait))
+      val superCalls = superCallsMap.getOrElse(sym, List.empty)
+      val superCallsSet = superCalls.toSet
+      val additional = superCalls.filter(t => !directlyInheritedTraitsSet(t) && t.is(Trait))
 //      if (additional.nonEmpty)
 //        println(s"$fullName: adding supertraits $additional")
-      directlyInheritedTraits.filter(t => !allBaseClasses(t) || superCalls(t)) ++ additional
+      directlyInheritedTraits.filter(t => !allBaseClasses(t) || superCallsSet(t)) ++ additional
     }
 
     val interfaces = classSym.superInterfaces.map(classBTypeFromSymbol)
diff --git a/compiler/src/dotty/tools/backend/jvm/DottyBackendInterface.scala b/compiler/src/dotty/tools/backend/jvm/DottyBackendInterface.scala
index 8016c2bfc209..cab17b31c3f3 100644
--- a/compiler/src/dotty/tools/backend/jvm/DottyBackendInterface.scala
+++ b/compiler/src/dotty/tools/backend/jvm/DottyBackendInterface.scala
@@ -25,7 +25,7 @@ import StdNames.nme
 import NameKinds.{LazyBitMapName, LazyLocalName}
 import Names.Name
 
-class DottyBackendInterface(val superCallsMap: ReadOnlyMap[Symbol, Set[ClassSymbol]])(using val ctx: Context) {
+class DottyBackendInterface(val superCallsMap: ReadOnlyMap[Symbol, List[ClassSymbol]])(using val ctx: Context) {
 
   private val desugared = new java.util.IdentityHashMap[Type, tpd.Select]
 
diff --git a/compiler/src/dotty/tools/backend/jvm/GenBCode.scala b/compiler/src/dotty/tools/backend/jvm/GenBCode.scala
index a616241d9a3e..f28c89b7817e 100644
--- a/compiler/src/dotty/tools/backend/jvm/GenBCode.scala
+++ b/compiler/src/dotty/tools/backend/jvm/GenBCode.scala
@@ -23,10 +23,10 @@ class GenBCode extends Phase { self =>
 
   override def isRunnable(using Context) = super.isRunnable && !ctx.usedBestEffortTasty
 
-  private val superCallsMap = new MutableSymbolMap[Set[ClassSymbol]]
+  private val superCallsMap = new MutableSymbolMap[List[ClassSymbol]]
   def registerSuperCall(sym: Symbol, calls: ClassSymbol): Unit = {
-    val old = superCallsMap.getOrElse(sym, Set.empty)
-    superCallsMap.update(sym, old + calls)
+    val old = superCallsMap.getOrElse(sym, List.empty)
+    superCallsMap.update(sym, old :+ calls)
   }
 
   private val entryPoints = new mutable.HashSet[String]()