diff --git a/compiler/src/dotty/tools/dotc/core/Denotations.scala b/compiler/src/dotty/tools/dotc/core/Denotations.scala
index a5e1f64d58cb..7d2af9f4bf8f 100644
--- a/compiler/src/dotty/tools/dotc/core/Denotations.scala
+++ b/compiler/src/dotty/tools/dotc/core/Denotations.scala
@@ -513,7 +513,7 @@ object Denotations {
     *  otherwise generate new synthetic names.
     */
   private def mergeParamNames(tp1: LambdaType, tp2: LambdaType): List[tp1.ThisName] =
-    (for ((name1, name2, idx) <- tp1.paramNames.lazyZip(tp2.paramNames).lazyZip(tp1.paramNames.indices))
+    (for case (name1, name2, idx) <- tp1.paramNames.lazyZip(tp2.paramNames).lazyZip(tp1.paramNames.indices)
       yield if (name1 == name2) name1 else tp1.companion.syntheticParamName(idx)).toList
 
   /** Normally, `tp1 & tp2`, with extra care taken to return `tp1` or `tp2` directly if that's
diff --git a/compiler/src/dotty/tools/dotc/core/Symbols.scala b/compiler/src/dotty/tools/dotc/core/Symbols.scala
index b19c8cae3105..9df013c8fb6e 100644
--- a/compiler/src/dotty/tools/dotc/core/Symbols.scala
+++ b/compiler/src/dotty/tools/dotc/core/Symbols.scala
@@ -754,7 +754,7 @@ object Symbols {
     }
     val tparams = tparamBuf.toList
     val bounds = boundsFn(trefBuf.toList)
-    for (tparam, bound) <- tparams.lazyZip(bounds) do
+    for case (tparam, bound) <- tparams.lazyZip(bounds) do
       tparam.info = bound
     tparams
   }
diff --git a/compiler/src/dotty/tools/dotc/transform/Splicer.scala b/compiler/src/dotty/tools/dotc/transform/Splicer.scala
index 1306aa87ae11..335dcb583913 100644
--- a/compiler/src/dotty/tools/dotc/transform/Splicer.scala
+++ b/compiler/src/dotty/tools/dotc/transform/Splicer.scala
@@ -307,7 +307,7 @@ object Splicer {
       def interpretArgsGroup(args: List[Tree], argTypes: List[Type]): List[Object] =
         assert(args.size == argTypes.size)
         val view =
-          for (arg, info) <- args.lazyZip(argTypes) yield
+          for case (arg, info) <- args.lazyZip(argTypes) yield
             info match
               case _: ExprType => () => interpretTree(arg) // by-name argument
               case _ => interpretTree(arg) // by-value argument
diff --git a/compiler/src/dotty/tools/dotc/typer/RefChecks.scala b/compiler/src/dotty/tools/dotc/typer/RefChecks.scala
index b14ea658b405..b62014ea79ac 100644
--- a/compiler/src/dotty/tools/dotc/typer/RefChecks.scala
+++ b/compiler/src/dotty/tools/dotc/typer/RefChecks.scala
@@ -140,7 +140,7 @@ object RefChecks {
         if parentCls.is(Trait) then
           val params = parentCls.asClass.paramGetters
           val args = termArgss(app).flatten
-          for (param, arg) <- params.lazyZip(args) do
+          for case (param, arg) <- params.lazyZip(args) do
             if !param.is(Private) then // its type can be narrowed through intersection -> a check is needed
               val paramType = cls.thisType.memberInfo(param)
               if !(arg.tpe <:< paramType) then