diff --git a/compiler/src/dotty/tools/dotc/config/Settings.scala b/compiler/src/dotty/tools/dotc/config/Settings.scala
index 7454682fba56..a5fc6a64aa45 100644
--- a/compiler/src/dotty/tools/dotc/config/Settings.scala
+++ b/compiler/src/dotty/tools/dotc/config/Settings.scala
@@ -47,6 +47,10 @@ object Settings:
         values(idx) = x
         changed.add(idx)
         this
+
+    def reinitializedCopy(): SettingsState =
+      SettingsState(values.toSeq, changed.toSet)
+
   end SettingsState
 
   case class ArgsSummary(
diff --git a/compiler/src/dotty/tools/dotc/inlines/Inlines.scala b/compiler/src/dotty/tools/dotc/inlines/Inlines.scala
index fffe87c3f57a..c1ab5f99d8d2 100644
--- a/compiler/src/dotty/tools/dotc/inlines/Inlines.scala
+++ b/compiler/src/dotty/tools/dotc/inlines/Inlines.scala
@@ -342,10 +342,13 @@ object Inlines:
         if Inlines.isInlineable(codeArg1.symbol) then stripTyped(Inlines.inlineCall(codeArg1))
         else codeArg1
 
+      // We should not be rewriting tested strings
+      val noRewriteSettings = ctx.settings.rewrite.updateIn(ctx.settingsState.reinitializedCopy(), None)
+
       ConstFold(underlyingCodeArg).tpe.widenTermRefExpr match {
         case ConstantType(Constant(code: String)) =>
           val source2 = SourceFile.virtual("tasty-reflect", code)
-          inContext(ctx.fresh.setNewTyperState().setTyper(new Typer(ctx.nestingLevel + 1)).setSource(source2)) {
+          inContext(ctx.fresh.setSettings(noRewriteSettings).setNewTyperState().setTyper(new Typer(ctx.nestingLevel + 1)).setSource(source2)) {
             val tree2 = new Parser(source2).block()
             if ctx.reporter.allErrors.nonEmpty then
               ctx.reporter.allErrors.map((ErrorKind.Parser, _))
diff --git a/compiler/test/dotc/pos-test-pickling.blacklist b/compiler/test/dotc/pos-test-pickling.blacklist
index b68ac7fc3b6e..032b53150e49 100644
--- a/compiler/test/dotc/pos-test-pickling.blacklist
+++ b/compiler/test/dotc/pos-test-pickling.blacklist
@@ -135,3 +135,6 @@ parsercombinators-new-syntax.scala
 hylolib-deferred-given
 hylolib-cb
 hylolib
+
+# typecheckErrors method unpickling
+i21415.scala
diff --git a/compiler/test/dotc/run-test-pickling.blacklist b/compiler/test/dotc/run-test-pickling.blacklist
index dacbc63bb520..31304e061bc7 100644
--- a/compiler/test/dotc/run-test-pickling.blacklist
+++ b/compiler/test/dotc/run-test-pickling.blacklist
@@ -27,7 +27,6 @@ tuple-zip.scala
 tuples1.scala
 tuples1a.scala
 tuples1b.scala
-typeCheckErrors.scala
 typeclass-derivation-doc-example.scala
 typeclass-derivation1.scala
 typeclass-derivation2.scala
@@ -47,3 +46,6 @@ trait-static-forwarder
 i17255
 named-tuples-strawman-2.scala
 
+# typecheckErrors method unpickling
+typeCheckErrors.scala
+
diff --git a/tests/pos/i21415.scala b/tests/pos/i21415.scala
new file mode 100644
index 000000000000..04afd512b535
--- /dev/null
+++ b/tests/pos/i21415.scala
@@ -0,0 +1,8 @@
+//> using options -rewrite -source:3.4-migration
+import scala.compiletime.testing.typeCheckErrors
+
+def foo(arg: Int): Unit = ???
+
+@main def Test =
+  typeCheckErrors("Seq.empty[Int].foreach(foo.apply _)")
+  typeCheckErrors("Seq.empty[Int].foreach(foo.apply _)")