diff --git a/src/Gui/Action.h b/src/Gui/Action.h
index 0a251c4f31..1693c1c1f5 100644
--- a/src/Gui/Action.h
+++ b/src/Gui/Action.h
@@ -46,7 +46,7 @@ class GuiExport Action : public QObject
     Q_OBJECT
 
 public:
-    Action (Command* pcCmd, QObject * parent = nullptr);
+    explicit Action (Command* pcCmd, QObject * parent = nullptr);
     /// Action takes ownership of the 'action' object.
     Action (Command* pcCmd, QAction* action, QObject * parent);
     virtual ~Action();
@@ -128,7 +128,7 @@ class GuiExport ActionGroup : public Action
     Q_OBJECT
 
 public:
-    ActionGroup (Command* pcCmd, QObject * parent = nullptr);
+    explicit ActionGroup (Command* pcCmd, QObject * parent = nullptr);
     virtual ~ActionGroup();
 
     void addTo (QWidget * w);
@@ -168,7 +168,7 @@ class GuiExport WorkbenchComboBox : public QComboBox
     Q_OBJECT
 
 public:
-    WorkbenchComboBox(WorkbenchGroup* wb, QWidget* parent=nullptr);
+    explicit WorkbenchComboBox(WorkbenchGroup* wb, QWidget* parent=nullptr);
     virtual ~WorkbenchComboBox();
     void showPopup();
 
@@ -227,7 +227,7 @@ class GuiExport RecentFilesAction : public ActionGroup
     Q_OBJECT
 
 public:
-    RecentFilesAction (Command* pcCmd, QObject * parent = nullptr);
+    explicit RecentFilesAction (Command* pcCmd, QObject * parent = nullptr);
     virtual ~RecentFilesAction();
 
     void appendFile(const QString&);
@@ -260,7 +260,7 @@ class GuiExport RecentMacrosAction : public ActionGroup
     Q_OBJECT
 
 public:
-    RecentMacrosAction (Command* pcCmd, QObject * parent = nullptr);
+    explicit RecentMacrosAction (Command* pcCmd, QObject * parent = nullptr);
     virtual ~RecentMacrosAction();
 
     void appendFile(const QString&);
@@ -293,7 +293,7 @@ class GuiExport UndoAction : public Action
     Q_OBJECT
 
 public:
-    UndoAction (Command* pcCmd,QObject * parent = nullptr);
+    explicit UndoAction (Command* pcCmd,QObject * parent = nullptr);
     ~UndoAction();
     void addTo (QWidget * w);
     void setEnabled(bool);
@@ -318,7 +318,7 @@ class GuiExport RedoAction : public Action
     Q_OBJECT
 
 public:
-    RedoAction (Command* pcCmd,QObject * parent = nullptr);
+    explicit RedoAction (Command* pcCmd,QObject * parent = nullptr);
     ~RedoAction();
     void addTo ( QWidget * w );
     void setEnabled(bool);
@@ -342,7 +342,7 @@ class GuiExport DockWidgetAction : public Action
     Q_OBJECT
 
 public:
-    DockWidgetAction (Command* pcCmd, QObject * parent = nullptr);
+    explicit DockWidgetAction (Command* pcCmd, QObject * parent = nullptr);
     virtual ~DockWidgetAction();
     void addTo (QWidget * w);
 
@@ -361,7 +361,7 @@ class GuiExport ToolBarAction : public Action
     Q_OBJECT
 
 public:
-    ToolBarAction (Command* pcCmd, QObject * parent = nullptr);
+    explicit ToolBarAction (Command* pcCmd, QObject * parent = nullptr);
     virtual ~ToolBarAction();
     void addTo (QWidget * w);
 
@@ -379,7 +379,7 @@ class GuiExport WindowAction : public ActionGroup
     Q_OBJECT
 
 public:
-    WindowAction (Command* pcCmd, QObject * parent = nullptr);
+    explicit WindowAction (Command* pcCmd, QObject * parent = nullptr);
     virtual ~WindowAction();
     void addTo (QWidget * w);
 
diff --git a/src/Gui/CMakeLists.txt b/src/Gui/CMakeLists.txt
index 053b701e8c..b442d9c3cd 100644
--- a/src/Gui/CMakeLists.txt
+++ b/src/Gui/CMakeLists.txt
@@ -862,8 +862,8 @@ SET(Quarter_MOC_HDR
 
 qt_wrap_cpp(Quarter_MOC_SRCS ${Quarter_MOC_HDR})
 
-SET(Quarter_SRCS 
-    ${Quarter_CPP_SRC} 
+SET(Quarter_SRCS
+    ${Quarter_CPP_SRC}
     ${Quarter_H_SRC}
     ${Quarter_MOC_SRCS}
 )
@@ -1128,7 +1128,7 @@ SET(FreeCADGui_CPP_SRCS
     ManualAlignment.cpp
     TransactionObject.cpp
 )
-SET(FreeCADGui_SRCS 
+SET(FreeCADGui_SRCS
     Application.h
     AutoSaver.h
     BitmapFactory.h
diff --git a/src/Gui/CommandCompleter.cpp b/src/Gui/CommandCompleter.cpp
index 7ec5844e7a..212744a8b0 100644
--- a/src/Gui/CommandCompleter.cpp
+++ b/src/Gui/CommandCompleter.cpp
@@ -55,7 +55,7 @@ class CommandModel : public QAbstractItemModel
     int revision = 0;
 
 public:
-    CommandModel(QObject* parent)
+    explicit CommandModel(QObject* parent)
         : QAbstractItemModel(parent)
     {
         update();
diff --git a/src/Gui/CommandCompleter.h b/src/Gui/CommandCompleter.h
index 18a3f35e1f..1f578e1909 100644
--- a/src/Gui/CommandCompleter.h
+++ b/src/Gui/CommandCompleter.h
@@ -41,7 +41,7 @@ class GuiExport CommandCompleter : public QCompleter
 {
     Q_OBJECT
 public:
-    CommandCompleter(QLineEdit *edit, QObject *parent = nullptr);
+    explicit CommandCompleter(QLineEdit *edit, QObject *parent = nullptr);
 
 Q_SIGNALS:
     /// Triggered when a command is selected in the completer
diff --git a/src/Gui/CommandPyImp.cpp b/src/Gui/CommandPyImp.cpp
index 50005c268f..f563cb287d 100644
--- a/src/Gui/CommandPyImp.cpp
+++ b/src/Gui/CommandPyImp.cpp
@@ -306,7 +306,7 @@ PyObject* CommandPy::createCustomCommand(PyObject* args, PyObject* kw)
     auto macro = new MacroCommand(name.c_str(), false);
     commandManager.addCommand(macro);
 
-    macro->setScriptName(macroFile); 
+    macro->setScriptName(macroFile);
 
     if (menuTxt)
         macro->setMenuText(menuTxt);
@@ -338,8 +338,8 @@ PyObject* CommandPy::removeCustomCommand(PyObject* args)
     CommandManager& commandManager = Application::Instance->commandManager();
     std::vector<Command*> macros = commandManager.getGroupCommands("Macros");
 
-    auto action = std::find_if(macros.begin(), macros.end(), [actionName](const Command* c) { 
-        return std::string(c->getName()) == std::string(actionName); 
+    auto action = std::find_if(macros.begin(), macros.end(), [actionName](const Command* c) {
+        return std::string(c->getName()) == std::string(actionName);
     });
 
     if (action != macros.end()) {
diff --git a/src/Gui/CommandView.cpp b/src/Gui/CommandView.cpp
index ca2c9737af..533a1b4373 100644
--- a/src/Gui/CommandView.cpp
+++ b/src/Gui/CommandView.cpp
@@ -2599,7 +2599,7 @@ void StdViewBoxZoom::activated(int iMsg)
         View3DInventorViewer* viewer = view->getViewer();
         if (!viewer->isSelecting()) {
             SelectionCallbackHandler::Create(viewer, View3DInventorViewer::BoxZoom, QCursor(QPixmap(cursor_box_zoom), 7, 7));
-		}
+        }
     }
 }
 
diff --git a/src/Gui/DlgKeyboard.ui b/src/Gui/DlgKeyboard.ui
index 0e8b9f0e27..5e2d77ca5e 100644
--- a/src/Gui/DlgKeyboard.ui
+++ b/src/Gui/DlgKeyboard.ui
@@ -182,10 +182,10 @@ be treated as shorctcut key sequence 'F, F'.</string>
            <property name="toolTip">
             <string>This list shows commands having the same shortcut in the priority from high
 to low. If more than one command with the same shortcut are active at the
-same time. The one with the highest prioirty will be triggered.</string>
+same time. The one with the highest priority will be triggered.</string>
            </property>
            <property name="text">
-            <string>Shorcut priority list:</string>
+            <string>Shortcut priority list:</string>
            </property>
           </widget>
          </item>
diff --git a/src/Gui/ShortcutManager.cpp b/src/Gui/ShortcutManager.cpp
index e56ff25b01..62d2034c99 100644
--- a/src/Gui/ShortcutManager.cpp
+++ b/src/Gui/ShortcutManager.cpp
@@ -322,10 +322,10 @@ bool ShortcutManager::eventFilter(QObject *o, QEvent *ev)
                 if (it->key.shortcut == action->shortcut() && it->key.name == name)
                     break;
                 QKeySequence oldShortcut = it->key.shortcut;
-                index.replace(it, {action, name});
+                index.replace(it, ActionData{action, name});
                 actionShortcutChanged(action, oldShortcut);
             } else {
-                index.insert({action, name});
+                index.insert(ActionData{action, name});
                 actionShortcutChanged(action, QKeySequence());
             }
         }
diff --git a/src/Gui/ShortcutManager.h b/src/Gui/ShortcutManager.h
index bca1f73c76..2af637b6ea 100644
--- a/src/Gui/ShortcutManager.h
+++ b/src/Gui/ShortcutManager.h
@@ -20,8 +20,8 @@
  *                                                                          *
  ****************************************************************************/
 
-#ifndef GUI_SHORTCUT_MANAGER_H 
-#define GUI_SHORTCUT_MANAGER_H 
+#ifndef GUI_SHORTCUT_MANAGER_H
+#define GUI_SHORTCUT_MANAGER_H
 
 #include <unordered_map>
 
@@ -108,7 +108,7 @@ private:
     struct ActionKey {
         QKeySequence shortcut;
         QByteArray name;
-        ActionKey(const QKeySequence &shortcut, const char *name = "")
+        explicit ActionKey(const QKeySequence &shortcut, const char *name = "")
             : shortcut(shortcut)
             , name(name)
         {}
@@ -126,7 +126,7 @@ private:
         intptr_t pointer;
         QPointer<QAction> action;
 
-        ActionData(QAction *action, const char *name = "")
+        explicit ActionData(QAction *action, const char *name = "")
             : key(action->shortcut(), name)
             , pointer(reinterpret_cast<intptr_t>(action))
             , action(action)
diff --git a/src/Gui/ToolBarManager.h b/src/Gui/ToolBarManager.h
index d2486e0162..778841dd01 100644
--- a/src/Gui/ToolBarManager.h
+++ b/src/Gui/ToolBarManager.h
@@ -26,6 +26,7 @@
 
 #include <string>
 #include <QStringList>
+#include <FCGlobal.h>
 
 class QAction;
 class QToolBar;
@@ -41,7 +42,7 @@ public:
     };
 
     ToolBarItem();
-    ToolBarItem(ToolBarItem* item, HideStyle forceHide = HideStyle::VISIBLE);
+    explicit ToolBarItem(ToolBarItem* item, HideStyle forceHide = HideStyle::VISIBLE);
     ~ToolBarItem();
 
     void setCommand(const std::string&);
diff --git a/src/Gui/Widgets.cpp b/src/Gui/Widgets.cpp
index c5940191bb..1b7975afd5 100644
--- a/src/Gui/Widgets.cpp
+++ b/src/Gui/Widgets.cpp
@@ -1255,7 +1255,7 @@ void StatusWidget::hideEvent(QHideEvent*)
 class LineNumberArea : public QWidget
 {
 public:
-    LineNumberArea(PropertyListEditor *editor) : QWidget(editor) {
+    explicit LineNumberArea(PropertyListEditor *editor) : QWidget(editor) {
         codeEditor = editor;
     }