diff --git a/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/FormatOps.scala b/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/FormatOps.scala
index d088ee4085..3dcf32febf 100644
--- a/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/FormatOps.scala
+++ b/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/FormatOps.scala
@@ -760,7 +760,8 @@ class FormatOps(
                 if (breakMany) TokenRanges.empty
                 else insideBracesBlock(nextFT, expire, true)
               Split(ModExt(newStmtMod.getOrElse(spaceMod)), cost)
-                .withSingleLine(expire, exclude)
+                .withSingleLineNoOptimal(expire, exclude)
+                .withOptimalToken(expire, ignore = cost != 0)
           }
         }
 
diff --git a/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/Router.scala b/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/Router.scala
index 7092f06720..3b492b6bd8 100644
--- a/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/Router.scala
+++ b/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/Router.scala
@@ -933,7 +933,7 @@ class Router(formatOps: FormatOps) {
             Seq(
               Split(Newline, nestedPenalty + Constants.ExceedColumnPenalty)
                 .withPolicy(newlinePolicy).withIndent(indent, close, Before),
-              Split(NoSplit, nestedPenalty).withSingleLine(breakToken)
+              Split(NoSplit, nestedPenalty).withSingleLineNoOptimal(breakToken)
                 .andPolicy(newlinePolicy & newlineAfterAssignDecision),
             )
           }
@@ -1276,7 +1276,7 @@ class Router(formatOps: FormatOps) {
           else NewlineT(alt = if (singleLineOnly) Some(NoSplit) else None)
         val nlSplit = Split(nlMod, bracketPenalty * (if (oneline) 4 else 2))
           .withIndent(indent)
-          .withSingleLineOpt(if (singleLineOnly) Some(close) else None)
+          .withSingleLineNoOptimal(close, ignore = !singleLineOnly)
           .andPolicy(nlPolicy & penalizeNewlinesPolicy, singleLineOnly)
           .andPolicyOpt(singleArgAsInfix.map(InfixSplits(_, ft).nlPolicy))
         Seq(noSplit, nlSplit)
diff --git a/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/Split.scala b/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/Split.scala
index 72786dc540..b541aa59d7 100644
--- a/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/Split.scala
+++ b/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/Split.scala
@@ -139,9 +139,17 @@ case class Split(
   ): Split =
     if (ignore) this else withOptimalAt(Some(OptimalToken(token, killOnFail)))
 
-  def withOptimalAt(optimalAt: => Option[OptimalToken]): Split = {
+  def withOptimalAt(fOptimalAt: => Option[OptimalToken]): Split = {
     require(this.optimalAt.isEmpty)
-    if (isIgnored) this else copy(optimalAt = optimalAt)
+    if (isIgnored) this
+    else {
+      val optimalAt = fOptimalAt
+      if (optimalAt.isEmpty) this
+      else {
+        require(cost == 0, s"can't set optimal, cost=$cost")
+        copy(optimalAt = optimalAt)
+      }
+    }
   }
 
   def withPolicy(newPolicy: => Policy, ignore: Boolean = false): Split =
@@ -168,15 +176,6 @@ case class Split(
       rank,
     )
 
-  def withSingleLineOpt(
-      expire: Option[Token],
-      exclude: => TokenRanges = TokenRanges.empty,
-      noSyntaxNL: Boolean = false,
-      killOnFail: Boolean = false,
-      rank: Int = 0,
-  )(implicit fileLine: FileLine, style: ScalafmtConfig): Split = expire
-    .fold(this)(withSingleLine(_, exclude, noSyntaxNL, killOnFail, rank))
-
   def withSingleLineAndOptimal(
       expire: Token,
       optimal: Token,
@@ -193,8 +192,10 @@ case class Split(
       exclude: => TokenRanges = TokenRanges.empty,
       noSyntaxNL: Boolean = false,
       rank: Int = 0,
+      ignore: Boolean = false,
   )(implicit fileLine: FileLine, style: ScalafmtConfig): Split = withPolicy(
     SingleLineBlock(expire, exclude, noSyntaxNL = noSyntaxNL, rank = rank),
+    ignore = ignore,
   )
 
   def withPolicyOpt(newPolicy: => Option[Policy]): Split =