diff --git a/.mise.toml b/.mise.toml
index ad6f21f9c..ef28ea4ce 100644
--- a/.mise.toml
+++ b/.mise.toml
@@ -1,6 +1,6 @@
 [tools]
 tuist = "4.23.0"
-swiftformat = "0.54.2"
+swiftformat = "0.58.7"
 
 [settings]
 # do not try to read versions from .nvmrc, .ruby-version, etc.
diff --git a/.swiftformat b/.swiftformat
index d8aeec83d..3d623e0dc 100644
--- a/.swiftformat
+++ b/.swiftformat
@@ -62,3 +62,7 @@
 --xcodeindentation disabled
 
 --disable unusedArguments
+
+# Preserve the existing rule set when upgrading from SwiftFormat 0.54.2.
+# Adopting these newer default rules is a separate style decision.
+--disable docCommentsBeforeModifiers,fileMacro,modifiersOnSameLine,preferCountWhere,redundantPublic,swiftTestingTestCaseNames
diff --git a/Samples/TicTacToe/Sources/Game/RunGameWorkflow.swift b/Samples/TicTacToe/Sources/Game/RunGameWorkflow.swift
index 7c10603ed..a89787977 100644
--- a/Samples/TicTacToe/Sources/Game/RunGameWorkflow.swift
+++ b/Samples/TicTacToe/Sources/Game/RunGameWorkflow.swift
@@ -123,7 +123,6 @@ extension RunGameWorkflow {
             ))
 
         case .maybeQuit:
-
             let takeTurnsScreen = TakeTurnsWorkflow(
                 playerX: state.playerX,
                 playerO: state.playerO
diff --git a/Samples/TicTacToe/Tests/TakeTurnsWorkflowTests.swift b/Samples/TicTacToe/Tests/TakeTurnsWorkflowTests.swift
index 9244a6881..15515d6c5 100644
--- a/Samples/TicTacToe/Tests/TakeTurnsWorkflowTests.swift
+++ b/Samples/TicTacToe/Tests/TakeTurnsWorkflowTests.swift
@@ -209,7 +209,6 @@ class TakeTurnsWorkflowTests: XCTestCase {
         TakeTurnsWorkflow(playerX: "X", playerO: "O")
             .renderTester(initialState: emptyBoardState)
             .render { screen in
-
                 // The display value for player X should match what was passed to the workflow.
                 XCTAssertEqual(screen.playerX, "X")
 
@@ -272,7 +271,6 @@ class TakeTurnsWorkflowTests: XCTestCase {
         TakeTurnsWorkflow(playerX: "X", playerO: "O")
             .renderTester(initialState: boardState)
             .render { screen in
-
                 // The display value for player X should match what was passed to the workflow.
                 XCTAssertEqual(screen.playerX, "X")
 
diff --git a/Samples/Tutorial/Frameworks/Tutorial5Complete/Tests/RootWorkflowTests.swift b/Samples/Tutorial/Frameworks/Tutorial5Complete/Tests/RootWorkflowTests.swift
index 4fd2af96a..2f155322a 100644
--- a/Samples/Tutorial/Frameworks/Tutorial5Complete/Tests/RootWorkflowTests.swift
+++ b/Samples/Tutorial/Frameworks/Tutorial5Complete/Tests/RootWorkflowTests.swift
@@ -188,7 +188,6 @@ class RootWorkflowTests: XCTestCase {
                     XCTFail("Expected a right bar button")
 
                 case .button(let button):
-
                     switch button.content {
                     case .text(let text):
                         XCTAssertEqual("Save", text)
diff --git a/WorkflowUI/Sources/Observation/WorkflowUIObserver.swift b/WorkflowUI/Sources/Observation/WorkflowUIObserver.swift
index 8487ad97c..137123df4 100644
--- a/WorkflowUI/Sources/Observation/WorkflowUIObserver.swift
+++ b/WorkflowUI/Sources/Observation/WorkflowUIObserver.swift
@@ -21,7 +21,7 @@ import Foundation
 /// **N.B. This is currently part of an experimental interface, and may have breaking changes in the future.**
 @_spi(ExperimentalObservation)
 public protocol WorkflowUIObserver {
-    func observeEvent<E: WorkflowUIEvent>(_ event: E)
+    func observeEvent(_ event: some WorkflowUIEvent)
 }
 
 // MARK: - Global Observation
diff --git a/WorkflowUI/Tests/UIViewControllerExtensionTests.swift b/WorkflowUI/Tests/UIViewControllerExtensionTests.swift
index 4417d80d6..394dfa849 100644
--- a/WorkflowUI/Tests/UIViewControllerExtensionTests.swift
+++ b/WorkflowUI/Tests/UIViewControllerExtensionTests.swift
@@ -72,7 +72,6 @@ class UIViewControllerExtensionTests: XCTestCase {
         let fixture = TestFixture(screen: Screen1(), environment: .empty)
 
         show(vc: fixture.root) { root in
-
             fixture.clearAllEvents()
 
             // Update to the same screen type should do nothing.