diff --git a/effects.cpp b/effects.cpp
index e15a505f31..a32a1e3101 100644
--- a/effects.cpp
+++ b/effects.cpp
@@ -60,8 +60,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "decorations/decorationbridge.h"
 #include <KDecoration2/DecorationSettings>
 
-#include <cassert>
-
 namespace KWin
 {
 //---------------------
diff --git a/effects/fallapart/fallapart.cpp b/effects/fallapart/fallapart.cpp
index 73f89d34b4..df623fb836 100644
--- a/effects/fallapart/fallapart.cpp
+++ b/effects/fallapart/fallapart.cpp
@@ -22,7 +22,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 // KConfigSkeleton
 #include "fallapartconfig.h"
 
-#include <cassert>
 #include <cmath>
 
 namespace KWin
diff --git a/effects/presentwindows/presentwindows.cpp b/effects/presentwindows/presentwindows.cpp
index 9211752fee..de58937f53 100644
--- a/effects/presentwindows/presentwindows.cpp
+++ b/effects/presentwindows/presentwindows.cpp
@@ -42,7 +42,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <QVector2D>
 #include <QVector4D>
 
-#include <cassert>
 #include <climits>
 #include <cmath>
 
diff --git a/group.cpp b/group.cpp
index 5528d97568..120c1cee35 100644
--- a/group.cpp
+++ b/group.cpp
@@ -37,9 +37,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <KWindowSystem>
 #include <QDebug>
 
-#include <cassert>
-
-
 /*
  TODO
  Rename as many uses of 'transient' as possible (hasTransient->hasSubwindow,etc.),
diff --git a/kcmkwin/kwinrules/ruleslist.cpp b/kcmkwin/kwinrules/ruleslist.cpp
index 22bdc99d66..f6180d7ab2 100644
--- a/kcmkwin/kwinrules/ruleslist.cpp
+++ b/kcmkwin/kwinrules/ruleslist.cpp
@@ -24,8 +24,6 @@
 
 #include "ruleswidget.h"
 
-#include <cassert>
-
 namespace KWin
 {
 
diff --git a/kcmkwin/kwinrules/ruleswidget.cpp b/kcmkwin/kwinrules/ruleswidget.cpp
index b57174eb33..1ff550093d 100644
--- a/kcmkwin/kwinrules/ruleswidget.cpp
+++ b/kcmkwin/kwinrules/ruleswidget.cpp
@@ -39,8 +39,6 @@
 
 #include "detectwidget.h"
 
-#include <cassert>
-
 Q_DECLARE_METATYPE(NET::WindowType)
 
 namespace KWin
diff --git a/layers.cpp b/layers.cpp
index 58180054c3..2bc33f296b 100644
--- a/layers.cpp
+++ b/layers.cpp
@@ -98,8 +98,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #include <QDebug>
 
-#include <cassert>
-
 namespace KWin
 {
 
diff --git a/libkwineffects/kwineffects.cpp b/libkwineffects/kwineffects.cpp
index 0c04afd0b3..06a3b735a7 100644
--- a/libkwineffects/kwineffects.cpp
+++ b/libkwineffects/kwineffects.cpp
@@ -41,8 +41,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <ksharedconfig.h>
 #include <kconfiggroup.h>
 
-#include <cassert>
-
 #include <KWayland/Server/surface_interface.h>
 
 #ifdef KWIN_HAVE_XRENDER_COMPOSITING
diff --git a/libkwineffects/kwineffects.h b/libkwineffects/kwineffects.h
index 3e2d710d17..173df50820 100644
--- a/libkwineffects/kwineffects.h
+++ b/libkwineffects/kwineffects.h
@@ -49,7 +49,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #include <netwm.h>
 
-#include <cassert>
 #include <climits>
 #include <functional>
 
diff --git a/placement.cpp b/placement.cpp
index 8f09336e55..406fb85ee5 100644
--- a/placement.cpp
+++ b/placement.cpp
@@ -34,8 +34,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <QRect>
 #include <QTextStream>
 
-#include <cassert>
-
 namespace KWin
 {
 
diff --git a/plugins/platforms/x11/standalone/glxbackend.cpp b/plugins/platforms/x11/standalone/glxbackend.cpp
index 2f6409beb1..d2bbc666a9 100644
--- a/plugins/platforms/x11/standalone/glxbackend.cpp
+++ b/plugins/platforms/x11/standalone/glxbackend.cpp
@@ -51,7 +51,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #if HAVE_DL_LIBRARY
 #include <dlfcn.h>
 #endif
-#include <cassert>
 
 #ifndef XCB_GLX_BUFFER_SWAP_COMPLETE
 #define XCB_GLX_BUFFER_SWAP_COMPLETE 1
diff --git a/plugins/platforms/x11/standalone/overlaywindow_x11.cpp b/plugins/platforms/x11/standalone/overlaywindow_x11.cpp
index 283fc545fd..05e70a5396 100644
--- a/plugins/platforms/x11/standalone/overlaywindow_x11.cpp
+++ b/plugins/platforms/x11/standalone/overlaywindow_x11.cpp
@@ -28,8 +28,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #include <QVector>
 
-#include <cassert>
-
 #include <xcb/composite.h>
 #include <xcb/shape.h>
 #if XCB_COMPOSITE_MAJOR_VERSION > 0 || XCB_COMPOSITE_MINOR_VERSION >= 3
diff --git a/toplevel.h b/toplevel.h
index e156546316..a9d1db06d0 100644
--- a/toplevel.h
+++ b/toplevel.h
@@ -39,7 +39,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <X11/Xlib.h>
 #include <fixx11h.h>
 // c++
-#include <cassert>
 #include <functional>
 
 class QOpenGLFramebufferObject;
diff --git a/utils.cpp b/utils.cpp
index 8884679161..9b8c437717 100644
--- a/utils.cpp
+++ b/utils.cpp
@@ -40,7 +40,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "platform.h"
 #include "workspace.h"
 
-#include <cassert>
 #include <csignal>
 #include <cstdio>