diff --git a/src/App/ExpressionVisitors.h b/src/App/ExpressionVisitors.h
index ea111821e9..e96825bc1e 100644
--- a/src/App/ExpressionVisitors.h
+++ b/src/App/ExpressionVisitors.h
@@ -25,6 +25,8 @@
 
 #include "Expression.h"
 
+#include "Document.h"
+
 namespace App
 {
 
diff --git a/src/Base/Sequencer.h b/src/Base/Sequencer.h
index 4d589cbf93..dc1c16886c 100644
--- a/src/Base/Sequencer.h
+++ b/src/Base/Sequencer.h
@@ -24,6 +24,9 @@
 #ifndef BASE_SEQUENCER_H
 #define BASE_SEQUENCER_H
 
+#include <cstddef>
+
+#include <FCGlobal.h>
 
 namespace Base
 {
diff --git a/src/Base/XMLTools.h b/src/Base/XMLTools.h
index d9526ddcc0..67ad517d58 100644
--- a/src/Base/XMLTools.h
+++ b/src/Base/XMLTools.h
@@ -30,6 +30,8 @@
 #include <xercesc/util/TransService.hpp>
 #include <xercesc/framework/MemoryManager.hpp>
 
+#include <FCGlobal.h>
+
 #ifndef XERCES_CPP_NAMESPACE_BEGIN
 #define XERCES_CPP_NAMESPACE_QUALIFIER
 namespace XERCES_CPP_NAMESPACE
diff --git a/src/Gui/CommandActionPy.h b/src/Gui/CommandActionPy.h
index c34281a7df..62756560ee 100644
--- a/src/Gui/CommandActionPy.h
+++ b/src/Gui/CommandActionPy.h
@@ -29,6 +29,7 @@
 
 namespace Gui
 {
+class Command;
 
 class CommandActionPy : public Py::PythonClass<CommandActionPy>
 {
diff --git a/src/Gui/MDIViewPy.h b/src/Gui/MDIViewPy.h
index 824423f199..53f7dc0021 100644
--- a/src/Gui/MDIViewPy.h
+++ b/src/Gui/MDIViewPy.h
@@ -29,6 +29,8 @@
 #include <QPointer>
 #include <FCGlobal.h>
 
+#include "MDIView.h"
+
 namespace Gui {
 class MDIView;
 
diff --git a/src/Gui/ManualAlignment.h b/src/Gui/ManualAlignment.h
index d881da101f..95b1f0a5bc 100644
--- a/src/Gui/ManualAlignment.h
+++ b/src/Gui/ManualAlignment.h
@@ -24,7 +24,9 @@
 #ifndef GUI_MANUALALIGNMENT_H
 #define GUI_MANUALALIGNMENT_H
 
+#include <QObject>
 #include <QPointer>
+
 #include <Base/BoundBox.h>
 #include <Base/Placement.h>
 #include <Base/Vector3D.h>
diff --git a/src/Gui/NotificationArea.h b/src/Gui/NotificationArea.h
index 9a60ac74e3..937473d8d4 100644
--- a/src/Gui/NotificationArea.h
+++ b/src/Gui/NotificationArea.h
@@ -32,6 +32,11 @@
 #include <Base/Observer.h>
 #include <Base/Parameter.h>
 
+namespace App
+{
+    class Document;
+}
+
 namespace Gui
 {
 
diff --git a/src/Gui/NotificationBox.h b/src/Gui/NotificationBox.h
index 5fb229f0a6..68b9c5dcdd 100644
--- a/src/Gui/NotificationBox.h
+++ b/src/Gui/NotificationBox.h
@@ -25,6 +25,10 @@
 
 #include <type_traits>
 
+#include <QFont>
+#include <QPoint>
+#include <QString>
+
 namespace Gui
 {
 
diff --git a/src/Gui/PreferencePackManager.h b/src/Gui/PreferencePackManager.h
index 5250b3407b..eabcf5f387 100644
--- a/src/Gui/PreferencePackManager.h
+++ b/src/Gui/PreferencePackManager.h
@@ -27,6 +27,10 @@
 #include <string>
 #include <mutex>
 
+#include <QMetaType>
+
+#include <FCGlobal.h>
+
 #include "App/Metadata.h"
 
 namespace Gui {
diff --git a/src/Gui/SoFCDB.h b/src/Gui/SoFCDB.h
index 8306474e68..0134fec018 100644
--- a/src/Gui/SoFCDB.h
+++ b/src/Gui/SoFCDB.h
@@ -28,6 +28,7 @@
 #include <string>
 #include <Inventor/C/basic.h>
 
+#include <FCGlobal.h>
 
 class SoNode;
 class SoGroup;
diff --git a/src/Gui/SoFCVectorizeU3DAction.h b/src/Gui/SoFCVectorizeU3DAction.h
index a83655e18b..de7e40eb9a 100644
--- a/src/Gui/SoFCVectorizeU3DAction.h
+++ b/src/Gui/SoFCVectorizeU3DAction.h
@@ -24,9 +24,11 @@
 #define GUI_SOFCVECTORIZEU3DACTION_H
 
 #include <fstream>
+
 #include <Inventor/annex/HardCopy/SoVectorizeAction.h>
 #include <Inventor/annex/HardCopy/SoVectorOutput.h>
 
+#include <FCGlobal.h>
 
 namespace Gui {
 
diff --git a/src/Gui/TaskDlgRelocation.h b/src/Gui/TaskDlgRelocation.h
index e8abe7b934..b9bd164559 100644
--- a/src/Gui/TaskDlgRelocation.h
+++ b/src/Gui/TaskDlgRelocation.h
@@ -27,9 +27,10 @@
 #include <Gui/TaskView/TaskDialog.h>
 #include <Gui/TaskView/TaskView.h>
 
+#include <FCGlobal.h>
 
-class Ui_DlgLocationPos;
-class ui_DlgLocationAngle;
+class Ui_Position;
+class Ui_Angle;
 
 namespace Gui {
 
diff --git a/src/Gui/TaskTransform.h b/src/Gui/TaskTransform.h
index 429ded08c0..171ce1f37d 100644
--- a/src/Gui/TaskTransform.h
+++ b/src/Gui/TaskTransform.h
@@ -29,6 +29,8 @@
 #include "ViewProviderDragger.h"
 
 #include <Base/ServiceProvider.h>
+
+#include <App/Application.h>
 #include <App/Services.h>
 
 class SoDragger;
diff --git a/src/Gui/WaitCursor.h b/src/Gui/WaitCursor.h
index 6b6505accf..86b6a3ae14 100644
--- a/src/Gui/WaitCursor.h
+++ b/src/Gui/WaitCursor.h
@@ -23,6 +23,7 @@
 #ifndef GUI_WAIT_CURSOR_H
 #define GUI_WAIT_CURSOR_H
 
+#include <FCGlobal.h>
 
 namespace Gui {