diff --git a/src/command/CloseAllWindowsButCurrentCommand.swift b/src/command/CloseAllWindowsButCurrentCommand.swift
index bd32324b..9e3181c4 100644
--- a/src/command/CloseAllWindowsButCurrentCommand.swift
+++ b/src/command/CloseAllWindowsButCurrentCommand.swift
@@ -1,6 +1,6 @@
 class CloseAllWindowsButCurrentCommand: Command {
     func runWithoutRefresh() {
-        precondition(Thread.current.isMainThread)
+        check(Thread.current.isMainThread)
         guard let focused = focusedWindowOrEffectivelyFocused else { return }
         for window in focused.workspace.allLeafWindowsRecursive {
             if window != focused {
diff --git a/src/command/CompositeCommand.swift b/src/command/CompositeCommand.swift
index 92c278e8..c8659ed0 100644
--- a/src/command/CompositeCommand.swift
+++ b/src/command/CompositeCommand.swift
@@ -2,7 +2,7 @@ struct CompositeCommand: Command { // todo drop
     let subCommands: [Command]
 
     func runWithoutRefresh() async {
-        precondition(Thread.current.isMainThread)
+        check(Thread.current.isMainThread)
         for command in subCommands {
             await command.runWithoutRefresh()
         }
diff --git a/src/command/ExecAndForgetCommand.swift b/src/command/ExecAndForgetCommand.swift
index 1a8570dc..ece145c9 100644
--- a/src/command/ExecAndForgetCommand.swift
+++ b/src/command/ExecAndForgetCommand.swift
@@ -2,7 +2,7 @@ struct ExecAndForgetCommand: Command {
     let bashCommand: String
 
     func runWithoutRefresh() {
-        precondition(Thread.current.isMainThread)
+        check(Thread.current.isMainThread)
         // It doesn't throw if exit code is non-zero
         try! Process.run(URL(filePath: "/bin/bash"), arguments: ["-c", bashCommand])
     }
diff --git a/src/command/ExecAndWaitCommand.swift b/src/command/ExecAndWaitCommand.swift
index f50151a7..b96a4161 100644
--- a/src/command/ExecAndWaitCommand.swift
+++ b/src/command/ExecAndWaitCommand.swift
@@ -2,7 +2,7 @@ struct ExecAndWaitCommand: Command {
     let bashCommand: String
 
     func runWithoutRefresh() async {
-        precondition(Thread.current.isMainThread)
+        check(Thread.current.isMainThread)
         await withCheckedContinuation { (continuation: CheckedContinuation<(), Never>) in
             let process = Process()
             process.executableURL = URL(filePath: "/bin/bash")
diff --git a/src/command/FlattenWorkspaceTreeCommand.swift b/src/command/FlattenWorkspaceTreeCommand.swift
index 1e3a450b..13ea1207 100644
--- a/src/command/FlattenWorkspaceTreeCommand.swift
+++ b/src/command/FlattenWorkspaceTreeCommand.swift
@@ -1,6 +1,6 @@
 struct FlattenWorkspaceTreeCommand: Command {
     func runWithoutRefresh() {
-        precondition(Thread.current.isMainThread)
+        check(Thread.current.isMainThread)
         guard let currentWindow = focusedWindowOrEffectivelyFocused else { return }
         let workspace = currentWindow.workspace
         let windows = workspace.rootTilingContainer.allLeafWindowsRecursive
diff --git a/src/command/FocusCommand.swift b/src/command/FocusCommand.swift
index 52593804..8165780e 100644
--- a/src/command/FocusCommand.swift
+++ b/src/command/FocusCommand.swift
@@ -2,7 +2,7 @@ struct FocusCommand: Command {
     let direction: CardinalDirection
 
     func runWithoutRefresh() {
-        precondition(Thread.current.isMainThread)
+        check(Thread.current.isMainThread)
         guard let currentWindow = focusedWindowOrEffectivelyFocused else { return }
         guard let (parent, ownIndex) = currentWindow.closestParent(hasChildrenInDirection: direction, withLayout: nil) else { return }
         let windowToFocus = parent.children[ownIndex + direction.focusOffset]
diff --git a/src/command/LayoutCommand.swift b/src/command/LayoutCommand.swift
index 3aaea5bb..1aa50737 100644
--- a/src/command/LayoutCommand.swift
+++ b/src/command/LayoutCommand.swift
@@ -11,7 +11,7 @@ struct LayoutCommand: Command {
     }
 
     func runWithoutRefresh() {
-        precondition(Thread.current.isMainThread)
+        check(Thread.current.isMainThread)
         guard let window = focusedWindowOrEffectivelyFocused else { return }
         let targetLayout: ConfigLayout = toggleBetween.firstIndex(of: window.configLayout)
             .flatMap { toggleBetween.getOrNil(atIndex: $0 + 1) }
diff --git a/src/command/ModeCommand.swift b/src/command/ModeCommand.swift
index 30333a6e..63d67599 100644
--- a/src/command/ModeCommand.swift
+++ b/src/command/ModeCommand.swift
@@ -2,7 +2,7 @@ struct ModeCommand: Command {
     let idToActivate: String
 
     func runWithoutRefresh() {
-        precondition(Thread.current.isMainThread)
+        check(Thread.current.isMainThread)
         activateMode(idToActivate)
     }
 }
diff --git a/src/command/MoveInCommand.swift b/src/command/MoveInCommand.swift
index 5161ea86..a6592486 100644
--- a/src/command/MoveInCommand.swift
+++ b/src/command/MoveInCommand.swift
@@ -2,7 +2,7 @@ struct MoveInCommand: Command {
     let direction: CardinalDirection
 
     func runWithoutRefresh() {
-        precondition(Thread.current.isMainThread)
+        check(Thread.current.isMainThread)
         guard let currentWindow = focusedWindowOrEffectivelyFocused else { return }
         guard let (parent, ownIndex) = currentWindow.closestParent(hasChildrenInDirection: direction, withLayout: nil) else { return }
         let moveInTarget = parent.children[ownIndex + direction.focusOffset]
diff --git a/src/command/MoveThroughCommand.swift b/src/command/MoveThroughCommand.swift
index bd899d89..186b80de 100644
--- a/src/command/MoveThroughCommand.swift
+++ b/src/command/MoveThroughCommand.swift
@@ -2,7 +2,7 @@ struct MoveThroughCommand: Command {
     let direction: CardinalDirection
 
     func runWithoutRefresh() {
-        precondition(Thread.current.isMainThread)
+        check(Thread.current.isMainThread)
         guard let currentWindow = focusedWindowOrEffectivelyFocused else { return }
         switch currentWindow.parent.kind {
         case .tilingContainer(let parent):
@@ -40,13 +40,13 @@ private func moveOut(window: Window, direction: CardinalDirection) {
     let bindToIndex: Int
     switch innerMostChild.parent.genericKind {
     case .tilingContainer(let parent):
-        precondition(parent.orientation == direction.orientation)
+        check(parent.orientation == direction.orientation)
         bindTo = parent
         bindToIndex = innerMostChild.ownIndex + direction.insertionOffset
     case .workspace(let parent): // create implicit container
         let prevRoot = parent.rootTilingContainer
         prevRoot.unbindFromParent()
-        precondition(prevRoot != parent.rootTilingContainer)
+        check(prevRoot != parent.rootTilingContainer)
         parent.rootTilingContainer.orientation = direction.orientation
         parent.rootTilingContainer.layout = .list // todo force List layout for implicit containers?
         prevRoot.bindTo(parent: parent.rootTilingContainer, adaptiveWeight: WEIGHT_AUTO)
diff --git a/src/command/MoveWorkspaceToDisplayCommand.swift b/src/command/MoveWorkspaceToDisplayCommand.swift
index f9a01a88..bda29918 100644
--- a/src/command/MoveWorkspaceToDisplayCommand.swift
+++ b/src/command/MoveWorkspaceToDisplayCommand.swift
@@ -6,7 +6,7 @@ struct MoveWorkspaceToDisplayCommand: Command {
     }
 
     func runWithoutRefresh() {
-        precondition(Thread.current.isMainThread)
+        check(Thread.current.isMainThread)
         let focusedWorkspace = Workspace.focused
         let prevMonitor = focusedWorkspace.monitor
         let sortedMonitors = sortedMonitors
diff --git a/src/command/ReloadConfigCommand.swift b/src/command/ReloadConfigCommand.swift
index bea7d61b..0503a3be 100644
--- a/src/command/ReloadConfigCommand.swift
+++ b/src/command/ReloadConfigCommand.swift
@@ -1,6 +1,6 @@
 struct ReloadConfigCommand: Command {
     func runWithoutRefresh() {
-        precondition(Thread.current.isMainThread)
+        check(Thread.current.isMainThread)
         reloadConfig()
     }
 }
diff --git a/src/command/ResizeCommand.swift b/src/command/ResizeCommand.swift
index de60d027..279c9907 100644
--- a/src/command/ResizeCommand.swift
+++ b/src/command/ResizeCommand.swift
@@ -7,7 +7,7 @@ struct ResizeCommand: Command { // todo cover with tests
     let diff: Int
 
     func runWithoutRefresh() { // todo support key repeat
-        precondition(Thread.current.isMainThread)
+        check(Thread.current.isMainThread)
         guard let window = focusedWindowOrEffectivelyFocused else { return }
 
         switch window.parent.kind {
diff --git a/src/command/WorkspaceBackAndForthCommand.swift b/src/command/WorkspaceBackAndForthCommand.swift
index 7eeb2aaf..8d63305d 100644
--- a/src/command/WorkspaceBackAndForthCommand.swift
+++ b/src/command/WorkspaceBackAndForthCommand.swift
@@ -1,6 +1,6 @@
 struct WorkspaceBackAndForthCommand: Command {
     func runWithoutRefresh() {
-        precondition(Thread.current.isMainThread)
+        check(Thread.current.isMainThread)
         guard let previousFocusedWorkspaceName else { return }
         WorkspaceCommand(workspaceName: previousFocusedWorkspaceName).runWithoutRefresh()
     }
diff --git a/src/command/WorkspaceCommand.swift b/src/command/WorkspaceCommand.swift
index 389b99f6..9673d963 100644
--- a/src/command/WorkspaceCommand.swift
+++ b/src/command/WorkspaceCommand.swift
@@ -2,7 +2,7 @@ struct WorkspaceCommand : Command {
     let workspaceName: String
 
     func runWithoutRefresh() {
-        precondition(Thread.current.isMainThread)
+        check(Thread.current.isMainThread)
         let workspace = Workspace.get(byName: workspaceName)
         // todo drop anyLeafWindowRecursive. It must not be necessary
         if let window = workspace.mostRecentWindow ?? workspace.anyLeafWindowRecursive { // switch to not empty workspace
@@ -16,7 +16,7 @@ struct WorkspaceCommand : Command {
             window.focus()
             // The switching itself will be done by refreshWorkspaces and layoutWorkspaces later in refresh
         } else { // switch to empty workspace
-            precondition(workspace.isEffectivelyEmpty)
+            check(workspace.isEffectivelyEmpty)
             workspace.monitor.setActiveWorkspace(workspace)
             focusedWorkspaceName = workspace.name
             focusedWorkspaceSourceOfTruth = .ownModel
diff --git a/src/focused.swift b/src/focused.swift
index 2a027d7c..1385efdc 100644
--- a/src/focused.swift
+++ b/src/focused.swift
@@ -5,7 +5,7 @@ var focusedApp: AeroApp? {
     if isUnitTest {
         return appForTests
     } else {
-        precondition(appForTests == nil)
+        check(appForTests == nil)
         if NSWorkspace.shared.frontmostApplication == _focusedApp {
             _focusedApp = nil
         }
diff --git a/src/mouse/resizeWithMouse.swift b/src/mouse/resizeWithMouse.swift
index b1e4a85b..ec9f6557 100644
--- a/src/mouse/resizeWithMouse.swift
+++ b/src/mouse/resizeWithMouse.swift
@@ -6,7 +6,7 @@ func resizedObs(_ obs: AXObserver, ax: AXUIElement, notif: CFString, data: Unsaf
 }
 
 func resetManipulatedWithMouseIfPossible() {
-    precondition(Thread.current.isMainThread)
+    check(Thread.current.isMainThread)
     if currentlyManipulatedWithMouseWindowId != nil {
         currentlyManipulatedWithMouseWindowId = nil
         for workspace in Workspace.all {
diff --git a/src/refresh.swift b/src/refresh.swift
index cf7a92b2..752e4f93 100644
--- a/src/refresh.swift
+++ b/src/refresh.swift
@@ -1,7 +1,7 @@
 /// It's one of the most important function of the whole application.
 /// The function is called as a feedback response on every user input
 func refresh(startup: Bool = false) {
-    precondition(Thread.current.isMainThread)
+    check(Thread.current.isMainThread)
     //debug("refresh \(Date.now.formatted(date: .abbreviated, time: .standard))")
 
     // Garbage collect terminated apps and windows before working with all windows
diff --git a/src/tree/AeroApp.swift b/src/tree/AeroApp.swift
index 764e46b4..19e7a1b6 100644
--- a/src/tree/AeroApp.swift
+++ b/src/tree/AeroApp.swift
@@ -7,10 +7,10 @@ class AeroApp: Hashable {
 
     static func ==(lhs: AeroApp, rhs: AeroApp) -> Bool {
         if lhs.id == rhs.id {
-            precondition(lhs === rhs)
+            check(lhs === rhs)
             return true
         } else {
-            precondition(lhs !== rhs)
+            check(lhs !== rhs)
             return false
         }
     }
diff --git a/src/tree/TreeNode.swift b/src/tree/TreeNode.swift
index c3d67ccd..f9f4cc6d 100644
--- a/src/tree/TreeNode.swift
+++ b/src/tree/TreeNode.swift
@@ -96,7 +96,7 @@ class TreeNode: Equatable {
         guard let _parent else { return nil }
 
         let index = _parent._children.remove(element: self) ?? errorT("Can't find child in its parent")
-        precondition(_parent._mruChildren.remove(self))
+        check(_parent._mruChildren.remove(self))
         self._parent = nil
 
         return BindingData(parent: _parent, adaptiveWeight: adaptiveWeight, index: index)
diff --git a/src/tree/TreeNodeEx.swift b/src/tree/TreeNodeEx.swift
index c7e14f3d..26a64584 100644
--- a/src/tree/TreeNodeEx.swift
+++ b/src/tree/TreeNodeEx.swift
@@ -110,7 +110,7 @@ extension TreeNode {
         })!
         switch innermostChild.parent?.kind {
         case .tilingContainer(let parent):
-            precondition(parent.orientation == direction.orientation)
+            check(parent.orientation == direction.orientation)
             return (parent, innermostChild.ownIndexOrNil!)
         case .workspace, nil:
             return nil
diff --git a/src/tree/Workspace.swift b/src/tree/Workspace.swift
index adb9288b..408f335d 100644
--- a/src/tree/Workspace.swift
+++ b/src/tree/Workspace.swift
@@ -158,7 +158,7 @@ private func rearrangeWorkspacesOnMonitors() {
     var preservedOldScreens: [CGPoint] = []
     for newScreen in newScreens {
         if let oldScreen = oldVisibleScreens.minBy({ ($0 - newScreen).vectorLength }) {
-            precondition(oldVisibleScreens.remove(oldScreen) != nil)
+            check(oldVisibleScreens.remove(oldScreen) != nil)
             newScreenToOldScreenMapping[newScreen] = oldScreen
             preservedOldScreens.append(oldScreen)
         }
diff --git a/src/util/accessibility.swift b/src/util/accessibility.swift
index af71e9a2..d6c18f65 100644
--- a/src/util/accessibility.swift
+++ b/src/util/accessibility.swift
@@ -197,7 +197,7 @@ enum Ax {
             key: kAXSizeAttribute,
             getter: {
                 var raw: CGSize = .zero
-                precondition(AXValueGetValue($0 as! AXValue, .cgSize, &raw))
+                check(AXValueGetValue($0 as! AXValue, .cgSize, &raw))
                 return raw
             },
             setter: {
@@ -272,7 +272,7 @@ extension AXUIElement {
 extension AXObserver {
     private static func newImpl(_ pid: pid_t, _ handler: AXObserverCallback) -> AXObserver {
         var observer: AXObserver? = nil
-        precondition(AXObserverCreate(pid, handler, &observer) == .success)
+        check(AXObserverCreate(pid, handler, &observer) == .success)
         return observer!
     }
 
diff --git a/src/util/util.swift b/src/util/util.swift
index a83aec2f..ef6739fa 100644
--- a/src/util/util.swift
+++ b/src/util/util.swift
@@ -5,6 +5,19 @@ func stringType(of some: Any) -> String {
     return string
 }
 
+func check(
+    _ condition: Bool,
+    _ message: String = "",
+    file: String = #file,
+    line: Int = #line,
+    column: Int = #column,
+    function: String = #function
+) {
+    if !condition {
+        error(message, file: file, line: line, column: column, function: function)
+    }
+}
+
 @inlinable func errorT<T>(
     _ message: String = "",
     file: String = #file,
diff --git a/test/testUtil.swift b/test/testUtil.swift
index db704966..3233c6f5 100644
--- a/test/testUtil.swift
+++ b/test/testUtil.swift
@@ -28,8 +28,8 @@ func setUpWorkspacesForTests() {
     focusedWorkspaceSourceOfTruth = .defaultSourceOfTruth
     focusedWorkspaceName = mainMonitor.activeWorkspace.name
     Workspace.garbageCollectUnusedWorkspaces()
-    precondition(Workspace.focused.isEffectivelyEmpty)
-    precondition(Workspace.focused === Workspace.all.singleOrNil(), Workspace.all.map(\.description).joined(separator: ", "))
+    check(Workspace.focused.isEffectivelyEmpty)
+    check(Workspace.focused === Workspace.all.singleOrNil(), Workspace.all.map(\.description).joined(separator: ", "))
 
     TestApp.shared.focusedWindow = nil
     TestApp.shared.windows = []
diff --git a/test/tree/TestApp.swift b/test/tree/TestApp.swift
index 509e8bb2..067c62e5 100644
--- a/test/tree/TestApp.swift
+++ b/test/tree/TestApp.swift
@@ -12,7 +12,7 @@ final class TestApp: AeroApp {
         get { _windows }
         set {
             if let focusedWindow {
-                precondition(newValue.contains(focusedWindow))
+                check(newValue.contains(focusedWindow))
             }
             _windows = newValue
         }
@@ -23,7 +23,7 @@ final class TestApp: AeroApp {
         get { _focusedWindow }
         set {
             if let window = newValue {
-                precondition(windows.contains(window))
+                check(windows.contains(window))
             }
             _focusedWindow = newValue
         }