diff --git a/.git-blame-ignore-revs b/.git-blame-ignore-revs
index e4f7fda7..231ef5cb 100644
--- a/.git-blame-ignore-revs
+++ b/.git-blame-ignore-revs
@@ -1,2 +1,5 @@
 # Scala Steward: Reformat with scalafmt 3.7.17
 98879bf22a5e11b4adf2047825c9efa0b9a22428
+
+# Scala Steward: Reformat with scalafmt 3.8.4
+2408d1e1bc244c7475e6bc184d43c6a49fed4a61
diff --git a/.scalafmt.conf b/.scalafmt.conf
index 3a9f1f18..28a13d04 100644
--- a/.scalafmt.conf
+++ b/.scalafmt.conf
@@ -1,4 +1,4 @@
-version = "3.7.17"
+version = "3.8.4"
 
 runner.dialect=scala213source3
 
diff --git a/modules/codecs/shared/src/test/scala/weaver/codecs/CodecsTest.scala b/modules/codecs/shared/src/test/scala/weaver/codecs/CodecsTest.scala
index 9631aa77..8521f054 100644
--- a/modules/codecs/shared/src/test/scala/weaver/codecs/CodecsTest.scala
+++ b/modules/codecs/shared/src/test/scala/weaver/codecs/CodecsTest.scala
@@ -39,7 +39,10 @@ object CodecsTest extends SimpleIOSuite {
   val outcomes = for {
     entry  <- entries
     result <- results
-  } yield TestOutcome.Default("outcome", 1.second, result, Chain.fromSeq(entries))
+  } yield TestOutcome.Default("outcome",
+                              1.second,
+                              result,
+                              Chain.fromSeq(entries))
 
   val messages =
     List(SuiteStarts("foo")) ++
diff --git a/modules/core/shared/src/main/scala-3/weaver/ExpectMacro.scala b/modules/core/shared/src/main/scala-3/weaver/ExpectMacro.scala
index 8f2349ee..29412a8d 100644
--- a/modules/core/shared/src/main/scala-3/weaver/ExpectMacro.scala
+++ b/modules/core/shared/src/main/scala-3/weaver/ExpectMacro.scala
@@ -48,7 +48,7 @@ private[weaver] object ExpectMacro {
    * contruct [[Expectations]].
    */
   def applyImpl[T: Type](assertion: Expr[Clues ?=> Boolean])(using
-  q: Quotes): Expr[Expectations] = {
+      q: Quotes): Expr[Expectations] = {
     val sourceLoc = weaver.macros.fromContextImpl(using q)
     '{
       val clues  = new Clues
@@ -81,7 +81,7 @@ private[weaver] object ExpectMacro {
    * part of the failed expectation.
    */
   def allImpl[T: Type](assertions: Expr[Seq[(Clues ?=> Boolean)]])(using
-  q: Quotes): Expr[Expectations] = {
+      q: Quotes): Expr[Expectations] = {
     val sourceLoc = weaver.macros.fromContextImpl(using q)
     '{
       val clues   = new Clues
diff --git a/modules/core/shared/src/main/scala/weaver/GlobalResourceF.scala b/modules/core/shared/src/main/scala/weaver/GlobalResourceF.scala
index 81a1721a..0b69a640 100644
--- a/modules/core/shared/src/main/scala/weaver/GlobalResourceF.scala
+++ b/modules/core/shared/src/main/scala/weaver/GlobalResourceF.scala
@@ -62,8 +62,8 @@ object GlobalResourceF {
 
     def putLazyR[A](
         resource: Resource[F, A],
-        label: Option[String] = None)(implicit
-    rt: ResourceTag[A]): Resource[F, Unit] =
+        label: Option[String] =
+          None)(implicit rt: ResourceTag[A]): Resource[F, Unit] =
       Resource.eval(putLazy(resource, label))
   }
 
@@ -114,7 +114,7 @@ object GlobalResourceF {
       implicit protected def F: MonadError[F, Throwable] = effect
 
       protected def rawGet[A](label: Option[String])(implicit
-      rt: ResourceTag[A]): F[Option[Either[A, Resource[F, A]]]] =
+          rt: ResourceTag[A]): F[Option[Either[A, Resource[F, A]]]] =
         effect.pure(None)
     }
   }
diff --git a/modules/framework-cats/jvm/src/test/scala/MetaJVM.scala b/modules/framework-cats/jvm/src/test/scala/MetaJVM.scala
index e49e0d2d..958e18dd 100644
--- a/modules/framework-cats/jvm/src/test/scala/MetaJVM.scala
+++ b/modules/framework-cats/jvm/src/test/scala/MetaJVM.scala
@@ -72,6 +72,7 @@ object MetaJVM {
           initialised <- Ref[IO].of(0)
           finalised   <- Ref[IO].of(0)
           totalUses   <- Ref[IO].of(0)
+
           /**
            * NOTE: the number 3 refers to the current number of instantiated
            * suites in the DogFoodTestsJVM spec, tests involving "global lazy
@@ -81,9 +82,7 @@ object MetaJVM {
            *
            *   - Change the number of LazyAccessParallel suites in "global lazy
            *     resources (parallel)" test
-           *
            *   - Change the number below
-           *
            *   - Add another test to the LazyAccessParallel spec below
            *
            * You are very likely to face a very confusing non-deterministic
diff --git a/modules/framework-cats/shared/src/test/scala/DogFoodTests.scala b/modules/framework-cats/shared/src/test/scala/DogFoodTests.scala
index 89d91b34..95a6eece 100644
--- a/modules/framework-cats/shared/src/test/scala/DogFoodTests.scala
+++ b/modules/framework-cats/shared/src/test/scala/DogFoodTests.scala
@@ -175,7 +175,8 @@ object DogFoodTests extends IOSuite {
           case LoggedEvent.Error(msg) => msg
         }.get
 
-        val expected = s"""
+        val expected =
+          s"""
         |- lots 0ms
         |  of
         |  multiline
@@ -323,7 +324,8 @@ object DogFoodTests extends IOSuite {
             msg
         }.get
 
-        val expected = s"""
+        val expected =
+          s"""
         |- (failure) 0ms
         |  assertion failed (modules/framework-cats/shared/src/test/scala/Meta.scala:83)
         |
@@ -346,7 +348,8 @@ object DogFoodTests extends IOSuite {
             msg
         }.get
 
-        val expected = s"""
+        val expected =
+          s"""
         |- (nested) 0ms
         |  assertion failed (modules/framework-cats/shared/src/test/scala/Meta.scala:89)
         |
@@ -370,7 +373,8 @@ object DogFoodTests extends IOSuite {
             msg
         }.get
 
-        val expected = s"""
+        val expected =
+          s"""
         |- (map) 0ms
         |  assertion failed (modules/framework-cats/shared/src/test/scala/Meta.scala:95)
         |
@@ -393,7 +397,8 @@ object DogFoodTests extends IOSuite {
             msg
         }.get
 
-        val expected = s"""
+        val expected =
+          s"""
         |- (show) 0ms
         |  assertion failed (modules/framework-cats/shared/src/test/scala/Meta.scala:102)
         |
@@ -417,7 +422,8 @@ object DogFoodTests extends IOSuite {
             msg
         }.get
 
-        val expected = s"""
+        val expected =
+          s"""
         |- (show-from-to-string) 0ms
         |  assertion failed (modules/framework-cats/shared/src/test/scala/Meta.scala:112)
         |
@@ -439,7 +445,8 @@ object DogFoodTests extends IOSuite {
             msg
         }.get
 
-        val expected = s"""
+        val expected =
+          s"""
         |- (helpers) 0ms
         |  assertion failed (modules/framework-cats/shared/src/test/scala/Meta.scala:121)
         |
diff --git a/modules/framework/cats/test/src-js-native/TestOutcomeEncodingTests.scala b/modules/framework/cats/test/src-js-native/TestOutcomeEncodingTests.scala
index 983ef611..3b6e3a1b 100644
--- a/modules/framework/cats/test/src-js-native/TestOutcomeEncodingTests.scala
+++ b/modules/framework/cats/test/src-js-native/TestOutcomeEncodingTests.scala
@@ -27,7 +27,7 @@ object TestOutcomeEncodingTests
   )
 
   private def roundtripTest(name: TestName, input: TestOutcomeNative)(implicit
-  loc: SourceLocation) = {
+      loc: SourceLocation) = {
 
     test(name.copy(name = "Roundtrip test - " + name.name)) {
       val encoded = TestOutcomeNative.encode(input)
diff --git a/scalafix/input/src/main/scala/fix/RenameAssertToExpectTest.scala b/scalafix/input/src/main/scala/fix/RenameAssertToExpectTest.scala
index 63785deb..55a358e7 100644
--- a/scalafix/input/src/main/scala/fix/RenameAssertToExpectTest.scala
+++ b/scalafix/input/src/main/scala/fix/RenameAssertToExpectTest.scala
@@ -1,6 +1,6 @@
 /*
 rule = RenameAssertToExpect
-*/
+ */
 package fix
 import weaver._
 
diff --git a/scalafix/output/src/main/scala/fix/RenameAssertToExpectTest.scala b/scalafix/output/src/main/scala/fix/RenameAssertToExpectTest.scala
index 4064e216..7f565ec2 100644
--- a/scalafix/output/src/main/scala/fix/RenameAssertToExpectTest.scala
+++ b/scalafix/output/src/main/scala/fix/RenameAssertToExpectTest.scala
@@ -20,4 +20,3 @@ object RenameAssertToExpectTest extends SimpleIOSuite {
     not(expect(2 == 1) xor expect(1 == 2))
   }
 }
-
diff --git a/scalafix/project/TargetAxis.scala b/scalafix/project/TargetAxis.scala
index ee368362..612cd27a 100644
--- a/scalafix/project/TargetAxis.scala
+++ b/scalafix/project/TargetAxis.scala
@@ -16,30 +16,32 @@ object TargetAxis {
   private def targetScalaVersion(virtualAxes: Seq[VirtualAxis]): String =
     virtualAxes.collectFirst { case a: TargetAxis => a.scalaVersion }.get
 
-  /** When invoked on a ProjectMatrix with a TargetAxis, lookup the project
-    * generated by `matrix` with a scalaVersion matching the one declared in
-    * that TargetAxis, and resolve `key`.
-    */
+  /**
+   * When invoked on a ProjectMatrix with a TargetAxis, lookup the project
+   * generated by `matrix` with a scalaVersion matching the one declared in that
+   * TargetAxis, and resolve `key`.
+   */
   def resolve[T](
       matrix: ProjectMatrix,
       key: TaskKey[T]
   ): Def.Initialize[Task[T]] =
     Def.taskDyn {
-      val sv = targetScalaVersion(virtualAxes.value)
+      val sv      = targetScalaVersion(virtualAxes.value)
       val project = matrix.finder().apply(sv)
       Def.task((project / key).value)
     }
 
-  /** When invoked on a ProjectMatrix with a TargetAxis, lookup the project
-    * generated by `matrix` with a scalaVersion matching the one declared in
-    * that TargetAxis, and resolve `key`.
-    */
+  /**
+   * When invoked on a ProjectMatrix with a TargetAxis, lookup the project
+   * generated by `matrix` with a scalaVersion matching the one declared in that
+   * TargetAxis, and resolve `key`.
+   */
   def resolve[T](
       matrix: ProjectMatrix,
       key: SettingKey[T]
   ): Def.Initialize[T] =
     Def.settingDyn {
-      val sv = targetScalaVersion(virtualAxes.value)
+      val sv      = targetScalaVersion(virtualAxes.value)
       val project = matrix.finder().apply(sv)
       Def.setting((project / key).value)
     }
diff --git a/scalafix/project/plugins.sbt b/scalafix/project/plugins.sbt
index 2b13486e..744be782 100644
--- a/scalafix/project/plugins.sbt
+++ b/scalafix/project/plugins.sbt
@@ -1,3 +1,3 @@
 resolvers += Resolver.sonatypeRepo("releases")
-addSbtPlugin("ch.epfl.scala" % "sbt-scalafix" % "0.11.1")
-addSbtPlugin("com.eed3si9n" % "sbt-projectmatrix" % "0.9.2")
+addSbtPlugin("ch.epfl.scala" % "sbt-scalafix"      % "0.11.1")
+addSbtPlugin("com.eed3si9n"  % "sbt-projectmatrix" % "0.9.2")
diff --git a/scalafix/rules/src/main/scala/fix/RenameAssertToExpect.scala b/scalafix/rules/src/main/scala/fix/RenameAssertToExpect.scala
index eded2ee9..9031bed4 100644
--- a/scalafix/rules/src/main/scala/fix/RenameAssertToExpect.scala
+++ b/scalafix/rules/src/main/scala/fix/RenameAssertToExpect.scala
@@ -5,7 +5,8 @@ import scalafix.v1._
 class RenameAssertToExpect extends SemanticRule("RenameAssertToExpect") {
 
   override def fix(implicit doc: SemanticDocument): Patch = {
-    val assertMethod  = SymbolMatcher.normalized("weaver/Expectations.Helpers#assert.")
+    val assertMethod =
+      SymbolMatcher.normalized("weaver/Expectations.Helpers#assert.")
     doc.tree.collect {
       case assertMethod(tree) => Patch.renameSymbol(tree.symbol, "expect")
     }.asPatch