diff --git a/CMakeLists.txt b/CMakeLists.txt
index 452602b103..c37f7ea036 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -193,7 +193,7 @@ if(Libdrm_FOUND)
 endif()
 
 find_package(gbm)
-set_package_properties(gbm PROPERTIES TYPE OPTIONAL PURPOSE "Required for egl ouput of drm backend.")
+set_package_properties(gbm PROPERTIES TYPE OPTIONAL PURPOSE "Required for egl output of drm backend.")
 set(HAVE_GBM FALSE)
 if(HAVE_DRM AND gbm_FOUND)
     set(HAVE_GBM TRUE)
diff --git a/appmenu.h b/appmenu.h
index 3e0ec8e0cb..9e6cee754f 100644
--- a/appmenu.h
+++ b/appmenu.h
@@ -19,8 +19,8 @@ GNU General Public License for more details.
 You should have received a copy of the GNU General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *********************************************************************/
-#ifndef KWIN_APPLICATIONMENU_H
-#define KWIN_APPLICATIONMENU_H
+#ifndef KWIN_APPMENU_H
+#define KWIN_APPMENU_H
 // KWin
 #include <kwinglobals.h>
 // Qt
@@ -72,4 +72,4 @@ private:
 
 }
 
-#endif // KWIN_APPLICATIONMENU_H
+#endif // KWIN_APPMENU_H
diff --git a/autotests/abstract_client.h b/autotests/abstract_client.h
index d5228a1e9f..55829175ed 100644
--- a/autotests/abstract_client.h
+++ b/autotests/abstract_client.h
@@ -1 +1 @@
-#include "mock_abstract_client.h"
\ No newline at end of file
+#include "mock_abstract_client.h"
diff --git a/autotests/integration/scripting/screenedge_test.cpp b/autotests/integration/scripting/screenedge_test.cpp
index 569304f426..1d85474013 100644
--- a/autotests/integration/scripting/screenedge_test.cpp
+++ b/autotests/integration/scripting/screenedge_test.cpp
@@ -25,7 +25,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "workspace.h"
 #include "scripting/scripting.h"
 #include "effect_builtins.h"
-#include "workspace.h"
 
 #define private public
 #include "screenedge.h"
diff --git a/autotests/test_xcb_wrapper.cpp b/autotests/test_xcb_wrapper.cpp
index fe0bcbae12..32719b5d5a 100644
--- a/autotests/test_xcb_wrapper.cpp
+++ b/autotests/test_xcb_wrapper.cpp
@@ -468,7 +468,7 @@ void TestXcbWrapper::testMotifEmpty()
 void TestXcbWrapper::testMotif_data()
 {
     QTest::addColumn<quint32>("flags");
-    QTest::addColumn<quint32>("funtions");
+    QTest::addColumn<quint32>("functions");
     QTest::addColumn<quint32>("decorations");
 
     QTest::addColumn<bool>("expectedHasDecoration");
@@ -503,11 +503,11 @@ void TestXcbWrapper::testMotif()
 {
     Atom atom(QByteArrayLiteral("_MOTIF_WM_HINTS"));
     QFETCH(quint32, flags);
-    QFETCH(quint32, funtions);
+    QFETCH(quint32, functions);
     QFETCH(quint32, decorations);
     quint32 data[] = {
         flags,
-        funtions,
+        functions,
         decorations,
         0,
         0
diff --git a/colorcorrection/colorcorrectdbusinterface.h b/colorcorrection/colorcorrectdbusinterface.h
index 1cb583c464..965b017020 100644
--- a/colorcorrection/colorcorrectdbusinterface.h
+++ b/colorcorrection/colorcorrectdbusinterface.h
@@ -84,10 +84,10 @@ public Q_SLOTS:
      * - EveningBeginFixed
      * - TransitionTime
      *
-     * It returns true if the configuration change was succesful, otherwise false.
+     * It returns true if the configuration change was successful, otherwise false.
      * A change request for the location or timings needs to provide all relevant fields at the same time
-     * to be succesful. Otherwise the whole change request will get ignored. A change request will be ignored
-     * as a whole as well, if one of the provided informations has been sent in a wrong format.
+     * to be successful. Otherwise the whole change request will get ignored. A change request will be ignored
+     * as a whole as well, if one of the provided information has been sent in a wrong format.
      *
      * @return bool
      * @see nightColorInfo
diff --git a/effects/flipswitch/flipswitch.cpp b/effects/flipswitch/flipswitch.cpp
index 5337979462..c72b953e5b 100644
--- a/effects/flipswitch/flipswitch.cpp
+++ b/effects/flipswitch/flipswitch.cpp
@@ -27,7 +27,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <QKeyEvent>
 #include <QMatrix4x4>
 
-#include <QAction>
 #include <KGlobalAccel>
 #include <KLocalizedString>
 
diff --git a/geometry.cpp b/geometry.cpp
index d732ee6da4..b2f3eaecfa 100644
--- a/geometry.cpp
+++ b/geometry.cpp
@@ -177,7 +177,7 @@ void Workspace::updateClientArea(bool force)
                         iS ++) {
                     const auto geo = new_sareas[ i ][ iS ].intersected(
                                                 (*it)->adjustedClientArea(desktopArea, screens[ iS ]));
-                    // ignore the geometry if it results in the screen getting removed completly
+                    // ignore the geometry if it results in the screen getting removed completely
                     if (!geo.isEmpty()) {
                         new_sareas[ i ][ iS ] = geo;
                     }
@@ -193,7 +193,7 @@ void Workspace::updateClientArea(bool force)
 //                            qDebug() << "adjusting new_sarea: " << screens[ iS ];
                 const auto geo = new_sareas[(*it)->desktop()][ iS ].intersected(
                       (*it)->adjustedClientArea(desktopArea, screens[ iS ]));
-                // ignore the geometry if it results in the screen getting removed completly
+                // ignore the geometry if it results in the screen getting removed completely
                 if (!geo.isEmpty()) {
                     new_sareas[(*it)->desktop()][ iS ] = geo;
                 }
diff --git a/input.cpp b/input.cpp
index de215cfef7..d1b3ecbd04 100644
--- a/input.cpp
+++ b/input.cpp
@@ -1229,7 +1229,7 @@ public:
     }
     bool touchDown(quint32 id, const QPointF &pos, quint32 time) override {
         Q_UNUSED(time)
-        // TODO: better check whether a touch sequence is in progess
+        // TODO: better check whether a touch sequence is in progress
         if (m_touchInProgress || waylandServer()->seat()->isTouchSequence()) {
             // cancel existing touch
             ScreenEdges::self()->gestureRecognizer()->cancelSwipeGesture();
diff --git a/kcmkwin/kwindecoration/decorationmodel.h b/kcmkwin/kwindecoration/decorationmodel.h
index 55c5f5c1fb..41af88d3e1 100644
--- a/kcmkwin/kwindecoration/decorationmodel.h
+++ b/kcmkwin/kwindecoration/decorationmodel.h
@@ -17,8 +17,8 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
-#ifndef KDECORATION_DECORATIONS_MODEL_H
-#define KDECORATION_DECORATIONS_MODEL_H
+#ifndef KDECORATION_DECORATION_MODEL_H
+#define KDECORATION_DECORATION_MODEL_H
 
 #include <QAbstractListModel>
 
diff --git a/libkwineffects/kwineffects.h b/libkwineffects/kwineffects.h
index 16bf5936ad..a439132ccc 100644
--- a/libkwineffects/kwineffects.h
+++ b/libkwineffects/kwineffects.h
@@ -546,7 +546,7 @@ public:
 
     /**
      * Reimplement this method to provide online debugging.
-     * This could be as trivial as printing specific detail informations about the effect state
+     * This could be as trivial as printing specific detail information about the effect state
      * but could also be used to move the effect in and out of a special debug modes, clear bogus
      * data, etc.
      * Notice that the functions is const by intent! Whenever you alter the state of the object
diff --git a/libkwineffects/kwinglobals.h b/libkwineffects/kwinglobals.h
index 0ca4891d78..bcedbfa38a 100644
--- a/libkwineffects/kwinglobals.h
+++ b/libkwineffects/kwinglobals.h
@@ -25,8 +25,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <QImage>
 #include <QPoint>
 #include <QVariant>
-#include <QCoreApplication>
-#include <QVariant>
 
 #include <kwin_export.h>
 
diff --git a/packageplugins/windowswitcher/windowswitcher.h b/packageplugins/windowswitcher/windowswitcher.h
index 74bbdcc8fc..141fcaf4d9 100644
--- a/packageplugins/windowswitcher/windowswitcher.h
+++ b/packageplugins/windowswitcher/windowswitcher.h
@@ -17,8 +17,8 @@
 *   Boston, MA 02110-1301, USA.                                               *
 *******************************************************************************/
 
-#ifndef SWITCHERPACKAGE_H
-#define SWITCHERPACKAGE_H
+#ifndef WINDOWSWITCHER_H
+#define WINDOWSWITCHER_H
 
 #include <KPackage/PackageStructure>
 
diff --git a/plugins/platforms/drm/drm_object.cpp b/plugins/platforms/drm/drm_object.cpp
index e67b581b5f..d2b7bb0d90 100644
--- a/plugins/platforms/drm/drm_object.cpp
+++ b/plugins/platforms/drm/drm_object.cpp
@@ -25,7 +25,7 @@ namespace KWin
 {
 
 /*
- * Defintions for class DrmObject
+ * Definitions for class DrmObject
  */
 
 DrmObject::DrmObject(uint32_t object_id, int fd)
@@ -91,7 +91,7 @@ bool DrmObject::atomicPopulate(drmModeAtomicReq *req)
 }
 
 /*
- * Defintions for struct Prop
+ * Definitions for struct Prop
  */
 
 DrmObject::Property::Property(drmModePropertyRes *prop, uint64_t val, QVector<QByteArray> enumNames)
diff --git a/plugins/platforms/drm/drm_object.h b/plugins/platforms/drm/drm_object.h
index 450dd491f5..25b9e02626 100644
--- a/plugins/platforms/drm/drm_object.h
+++ b/plugins/platforms/drm/drm_object.h
@@ -85,7 +85,7 @@ protected:
     const uint32_t m_id;
     DrmOutput *m_output = nullptr;
 
-    // for comparision with received name of DRM object
+    // for comparison with received name of DRM object
     QVector<Property *> m_props;
 
     class Property
diff --git a/plugins/platforms/hwcomposer/screens_hwcomposer.h b/plugins/platforms/hwcomposer/screens_hwcomposer.h
index b4de1cbe3b..384236d9ad 100644
--- a/plugins/platforms/hwcomposer/screens_hwcomposer.h
+++ b/plugins/platforms/hwcomposer/screens_hwcomposer.h
@@ -17,8 +17,8 @@ GNU General Public License for more details.
 You should have received a copy of the GNU General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *********************************************************************/
-#ifndef KWIN_SCREENS_FRAMEBUFFER_H
-#define KWIN_SCREENS_FRAMEBUFFER_H
+#ifndef KWIN_SCREENS_HWCOMPOSER_H
+#define KWIN_SCREENS_HWCOMPOSER_H
 #include "screens.h"
 
 namespace KWin
diff --git a/plugins/platforms/x11/standalone/windowselector.h b/plugins/platforms/x11/standalone/windowselector.h
index 5e1cbab332..710acd8aa4 100644
--- a/plugins/platforms/x11/standalone/windowselector.h
+++ b/plugins/platforms/x11/standalone/windowselector.h
@@ -20,8 +20,8 @@ You should have received a copy of the GNU General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *********************************************************************/
 
-#ifndef KWIN_KILLWINDOW_H
-#define KWIN_KILLWINDOW_H
+#ifndef KWIN_WINDOWSELECTOR_H
+#define KWIN_WINDOWSELECTOR_H
 
 #include "x11eventfilter.h"
 
diff --git a/plugins/platforms/x11/standalone/x11_platform.h b/plugins/platforms/x11/standalone/x11_platform.h
index 3cfdb47df1..7321775378 100644
--- a/plugins/platforms/x11/standalone/x11_platform.h
+++ b/plugins/platforms/x11/standalone/x11_platform.h
@@ -17,8 +17,8 @@ GNU General Public License for more details.
 You should have received a copy of the GNU General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *********************************************************************/
-#ifndef KWIN_X11STANDALONE_PLATFORM_H
-#define KWIN_X11STANDALONE_PLATFORM_H
+#ifndef KWIN_X11_PLATFORM_H
+#define KWIN_X11_PLATFORM_H
 #include "platform.h"
 
 #include <kwin_export.h>
diff --git a/screenedge.cpp b/screenedge.cpp
index 4d60672aa8..4d60722f38 100644
--- a/screenedge.cpp
+++ b/screenedge.cpp
@@ -274,9 +274,9 @@ void Edge::markAsTriggered(const QPoint &cursorPos, const QDateTime &triggerTime
 
 bool Edge::canActivate(const QPoint &cursorPos, const QDateTime &triggerTime)
 {
-    // we check whether either the timer has explicitly been invalidated (successfull trigger) or is
+    // we check whether either the timer has explicitly been invalidated (successful trigger) or is
     // bigger than the reactivation threshold (activation "aborted", usually due to moving away the cursor
-    // from the corner after successfull activation)
+    // from the corner after successful activation)
     // either condition means that "this is the first event in a new attempt"
     if (!m_lastReset.isValid() || m_lastReset.msecsTo(triggerTime) > edges()->reActivationThreshold()) {
         m_lastReset = triggerTime;
diff --git a/shell_client.cpp b/shell_client.cpp
index 51d69efbbc..a3a80cd532 100644
--- a/shell_client.cpp
+++ b/shell_client.cpp
@@ -27,7 +27,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "wayland_server.h"
 #include "workspace.h"
 #include "virtualdesktops.h"
-#include "workspace.h"
 #include "screens.h"
 #include "decorations/decorationbridge.h"
 #include "decorations/decoratedclient.h"
diff --git a/tabbox/clientmodel.h b/tabbox/clientmodel.h
index f08295f4f2..5815bc1920 100644
--- a/tabbox/clientmodel.h
+++ b/tabbox/clientmodel.h
@@ -76,7 +76,7 @@ public:
     /**
     * Generates a new list of TabBoxClients based on the current config.
     * Calling this method will reset the model. If partialReset is true
-    * the top of the list is kept as a starting point. If not the the
+    * the top of the list is kept as a starting point. If not the
     * current active client is used as the starting point to generate the
     * list.
     * @param desktop The desktop for which the list should be created
diff --git a/tabbox/switcheritem.h b/tabbox/switcheritem.h
index 4464a7f979..53c7ca829d 100644
--- a/tabbox/switcheritem.h
+++ b/tabbox/switcheritem.h
@@ -17,8 +17,8 @@ GNU General Public License for more details.
 You should have received a copy of the GNU General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *********************************************************************/
-#ifndef KWIN_TABBOX_ITEM
-#define KWIN_TABBOX_ITEM
+#ifndef KWIN_TABBOX_SWITCHERITEM_H
+#define KWIN_TABBOX_SWITCHERITEM_H
 
 #include <QObject>
 #include <QRect>
@@ -115,4 +115,4 @@ inline QObject *SwitcherItem::item() const
 } // TabBox
 } // KWin
 
-#endif // KWIN_TABBOX_ITEM
+#endif // KWIN_TABBOX_SWITCHERITEM_H
diff --git a/thumbnailitem.cpp b/thumbnailitem.cpp
index 469d4e1822..a0f3f47e8a 100644
--- a/thumbnailitem.cpp
+++ b/thumbnailitem.cpp
@@ -24,7 +24,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "composite.h"
 #include "effects.h"
 #include "workspace.h"
-#include "composite.h"
 #include "shell_client.h"
 #include "wayland_server.h"
 // Qt
diff --git a/virtualkeyboard.h b/virtualkeyboard.h
index 9240e99175..1bc56c0f63 100644
--- a/virtualkeyboard.h
+++ b/virtualkeyboard.h
@@ -17,8 +17,8 @@ GNU General Public License for more details.
 You should have received a copy of the GNU General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *********************************************************************/
-#ifndef KWIN_INPUT_METHODS_H
-#define KWIN_INPUT_METHODS_H
+#ifndef KWIN_VIRTUAL_KEYBOARD_H
+#define KWIN_VIRTUAL_KEYBOARD_H
 
 #include <QObject>
 
diff --git a/xcbutils.h b/xcbutils.h
index f21596aa16..011af83de1 100644
--- a/xcbutils.h
+++ b/xcbutils.h
@@ -1397,7 +1397,7 @@ public:
     void map();
     void unmap();
     void reparent(xcb_window_t parent, int x = 0, int y = 0);
-    void changeProperty(xcb_atom_t property, xcb_atom_t type, uint8_t format, uint32_t lenght,
+    void changeProperty(xcb_atom_t property, xcb_atom_t type, uint8_t format, uint32_t length,
                         const void *data, uint8_t mode = XCB_PROP_MODE_REPLACE);
     void deleteProperty(xcb_atom_t property);
     void setBorderWidth(uint32_t width);
@@ -1601,12 +1601,12 @@ void Window::reparent(xcb_window_t parent, int x, int y)
 }
 
 inline
-void Window::changeProperty(xcb_atom_t property, xcb_atom_t type, uint8_t format, uint32_t lenght, const void *data, uint8_t mode)
+void Window::changeProperty(xcb_atom_t property, xcb_atom_t type, uint8_t format, uint32_t length, const void *data, uint8_t mode)
 {
     if (!isValid()) {
         return;
     }
-    xcb_change_property(connection(), mode, m_window, property, type, format, lenght, data);
+    xcb_change_property(connection(), mode, m_window, property, type, format, length, data);
 }
 
 inline