diff --git a/scalafmt-core/shared/src/main/scala/org/scalafmt/config/Align.scala b/scalafmt-core/shared/src/main/scala/org/scalafmt/config/Align.scala
index e98a562de3..bb6fb5ff9c 100644
--- a/scalafmt-core/shared/src/main/scala/org/scalafmt/config/Align.scala
+++ b/scalafmt-core/shared/src/main/scala/org/scalafmt/config/Align.scala
@@ -158,13 +158,11 @@ object Align {
   implicit val alignTokensDecoder: ConfDecoderEx[Seq[AlignToken]] = AlignToken
     .seqDecoder.except { case (_, conf) =>
       preset.lift(conf).map(x => Configured.Ok(x.tokens))
-    }.contramap {
-      case Conf.Obj(List(("add", c))) =>
-        Console.err.println(
-          """'align.tokens.add' is deprecated; use align.tokens."+" instead.""",
-        )
-        Conf.Obj("+" -> c)
-      case conf => conf
+    }.contramapPartial { case Conf.Obj(List(("add", c))) =>
+      Console.err.println(
+        """'align.tokens.add' is deprecated; use align.tokens."+" instead.""",
+      )
+      Conf.Obj("+" -> c)
     }
 
 }
diff --git a/scalafmt-core/shared/src/main/scala/org/scalafmt/config/IndentOperator.scala b/scalafmt-core/shared/src/main/scala/org/scalafmt/config/IndentOperator.scala
index 2eea364e3d..8c120d1b43 100644
--- a/scalafmt-core/shared/src/main/scala/org/scalafmt/config/IndentOperator.scala
+++ b/scalafmt-core/shared/src/main/scala/org/scalafmt/config/IndentOperator.scala
@@ -109,8 +109,8 @@ object IndentOperator {
 
   val boolToAssign: PartialFunction[Conf, Conf] = { case Conf.Bool(value) =>
     if (value) Conf.Obj(
-      exemptScopeName -> Conf.nameOf(Exempt.notAssign),
-      Conf.nameOf(default.excludeRegex).value -> Conf.Str(".*"),
+      (exemptScopeName, Conf.nameOf(Exempt.notAssign)),
+      (Conf.nameOf(default.excludeRegex), Conf.Str(".*")),
     )
     else Conf.Obj.empty
   }
diff --git a/scalafmt-core/shared/src/main/scala/org/scalafmt/config/Newlines.scala b/scalafmt-core/shared/src/main/scala/org/scalafmt/config/Newlines.scala
index 983226d342..7e2d249edb 100644
--- a/scalafmt-core/shared/src/main/scala/org/scalafmt/config/Newlines.scala
+++ b/scalafmt-core/shared/src/main/scala/org/scalafmt/config/Newlines.scala
@@ -810,10 +810,8 @@ object Newlines {
       .deriveSurface[SelectChain]
     implicit val encoder: ConfEncoder[SelectChain] = generic.deriveEncoder
     implicit val decoder: ConfDecoderEx[SelectChain] = generic
-      .deriveDecoderEx(default).noTypos.contramap {
-        case conf: Conf.Str => Conf.Obj("style" -> conf)
-        case conf => conf
-      }
+      .deriveDecoderEx(default).noTypos
+      .contramapPartial { case conf: Conf.Str => Conf.Obj("style" -> conf) }
   }
 
 }
diff --git a/scalafmt-core/shared/src/main/scala/org/scalafmt/config/Presets.scala b/scalafmt-core/shared/src/main/scala/org/scalafmt/config/Presets.scala
index bdd385a365..ac6055da42 100644
--- a/scalafmt-core/shared/src/main/scala/org/scalafmt/config/Presets.scala
+++ b/scalafmt-core/shared/src/main/scala/org/scalafmt/config/Presets.scala
@@ -6,13 +6,11 @@ object Presets {
 
   val presetKey = "preset"
 
-  def contramap[A <: Product](
-      baseDecoder: ConfDecoderEx[A],
-  )(f: PartialFunction[Conf, Conf]): ConfDecoderEx[A] = baseDecoder.contramap {
-    case conf @ Conf.Obj(v) => v.collectFirst { case (`presetKey`, x) => x }
-        .flatMap(f.lift.apply)
-        .fold(conf)(x => Conf.Obj((presetKey -> x) :: v.filter(_._1 != presetKey)))
-    case conf => conf
+  def contramap[A <: Product](baseDecoder: ConfDecoderEx[A])(
+      f: PartialFunction[Conf, Conf],
+  ): ConfDecoderEx[A] = baseDecoder.contramapPartialOpt { case Conf.Obj(v) =>
+    v.collectFirst { case (`presetKey`, x) => x }.flatMap(f.lift.apply)
+      .map(x => Conf.Obj((presetKey -> x) :: v.filter(_._1 != presetKey)))
   }
 
   def mapDecoder[A <: Product](
diff --git a/scalafmt-core/shared/src/main/scala/org/scalafmt/config/RewriteScala3Settings.scala b/scalafmt-core/shared/src/main/scala/org/scalafmt/config/RewriteScala3Settings.scala
index 0dd93642a0..ffb3c96fab 100644
--- a/scalafmt-core/shared/src/main/scala/org/scalafmt/config/RewriteScala3Settings.scala
+++ b/scalafmt-core/shared/src/main/scala/org/scalafmt/config/RewriteScala3Settings.scala
@@ -67,14 +67,13 @@ object RewriteScala3Settings {
 
     implicit final val decoder: ConfDecoderEx[RemoveOptionalBraces] = generic
       .deriveDecoderEx[RemoveOptionalBraces](no).noTypos.detectSectionRenames
-      .contramap {
+      .contramapPartial {
         case Conf.Bool(true) | Conf.Str("yes") => Conf
             .Obj("enabled" -> Conf(true))
         case Conf.Bool(false) | Conf.Str("no") => Conf
             .Obj("enabled" -> Conf(false))
         case Conf.Str("oldSyntaxToo") => Conf
             .Obj("enabled" -> Conf(true), "oldSyntaxToo" -> Conf(true))
-        case conf => conf
       }
 
   }