diff --git a/cli/cppcheckexecutor.cpp b/cli/cppcheckexecutor.cpp
index 18a0c334d..aaf85170c 100644
--- a/cli/cppcheckexecutor.cpp
+++ b/cli/cppcheckexecutor.cpp
@@ -29,7 +29,6 @@
 #include "pathmatch.h"
 #include "preprocessor.h"
 #include "settings.h"
-#include "standards.h"
 #include "suppressions.h"
 #include "threadexecutor.h"
 #include "utils.h"
diff --git a/cli/threadexecutor.h b/cli/threadexecutor.h
index 408b665ef..638366de7 100644
--- a/cli/threadexecutor.h
+++ b/cli/threadexecutor.h
@@ -19,8 +19,8 @@
 #ifndef THREADEXECUTOR_H
 #define THREADEXECUTOR_H
 
+#include "config.h"
 #include "errorlogger.h"
-#include "importproject.h"
 
 #include <cstddef>
 #include <list>
@@ -32,6 +32,8 @@
 #elif defined(_WIN32)
 #define THREADING_MODEL_WIN
 #include <windows.h>
+
+#include "importproject.h"
 #endif
 
 class Settings;
diff --git a/gui/checkthread.h b/gui/checkthread.h
index c92ff2d4a..3923138bd 100644
--- a/gui/checkthread.h
+++ b/gui/checkthread.h
@@ -22,10 +22,10 @@
 
 #include <QThread>
 #include "cppcheck.h"
-#include "threadresult.h"
 #include "suppressions.h"
 
 class Settings;
+class ThreadResult;
 
 /// @addtogroup GUI
 /// @{
diff --git a/gui/codeeditor.cpp b/gui/codeeditor.cpp
index 9219008b6..a44e351c1 100644
--- a/gui/codeeditor.cpp
+++ b/gui/codeeditor.cpp
@@ -1,6 +1,7 @@
 #include <QtWidgets>
 #include <QShortcut>
 #include "codeeditor.h"
+#include "codeeditorstyle.h"
 
 
 Highlighter::Highlighter(QTextDocument *parent,
diff --git a/gui/codeeditor.h b/gui/codeeditor.h
index 3f4f2b92c..ed73a3015 100644
--- a/gui/codeeditor.h
+++ b/gui/codeeditor.h
@@ -5,16 +5,13 @@
 #include <QPlainTextEdit>
 #include <QObject>
 #include <QRegularExpression>
-#include "codeeditorstyle.h"
 
+class CodeEditorStyle;
 class QPaintEvent;
 class QResizeEvent;
 class QSize;
 class QWidget;
 
-class LineNumberArea;
-
-
 class Highlighter : public QSyntaxHighlighter {
     Q_OBJECT
 
diff --git a/gui/codeeditstyledialog.cpp b/gui/codeeditstyledialog.cpp
index 0e1701f52..4b4aaf97a 100644
--- a/gui/codeeditstyledialog.cpp
+++ b/gui/codeeditstyledialog.cpp
@@ -16,7 +16,9 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include "codeeditor.h"
 #include "codeeditstyledialog.h"
+#include "codeeditstylecontrols.h"
 #include <QHBoxLayout>
 #include <QVBoxLayout>
 #include <QFormLayout>
diff --git a/gui/codeeditstyledialog.h b/gui/codeeditstyledialog.h
index dfe424de1..08ff8024d 100644
--- a/gui/codeeditstyledialog.h
+++ b/gui/codeeditstyledialog.h
@@ -21,10 +21,12 @@
 
 #include <QDialog>
 #include <QPushButton>
-#include "codeeditstylecontrols.h"
-#include "codeeditor.h"
 #include "codeeditorstyle.h"
 
+class CodeEditor;
+class SelectColorButton;
+class SelectFontWeightCombo;
+
 class StyleEditDialog : public QDialog {
     Q_OBJECT
 public:
diff --git a/gui/csvreport.cpp b/gui/csvreport.cpp
index d67233b9d..b886ede20 100644
--- a/gui/csvreport.cpp
+++ b/gui/csvreport.cpp
@@ -20,6 +20,7 @@
 #include <QString>
 #include <QDir>
 #include <QTextStream>
+#include "erroritem.h"
 #include "report.h"
 #include "csvreport.h"
 
diff --git a/gui/erroritem.h b/gui/erroritem.h
index ab16ed887..342f33341 100644
--- a/gui/erroritem.h
+++ b/gui/erroritem.h
@@ -24,8 +24,6 @@
 #include <QMetaType>
 #include "errorlogger.h"
 
-class ErrorLine;
-
 /// @addtogroup GUI
 /// @{
 
diff --git a/gui/printablereport.cpp b/gui/printablereport.cpp
index 17ec50f34..e228c4bc7 100644
--- a/gui/printablereport.cpp
+++ b/gui/printablereport.cpp
@@ -16,6 +16,7 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include "erroritem.h"
 #include "printablereport.h"
 #include <QDir>
 
diff --git a/gui/projectfile.cpp b/gui/projectfile.cpp
index d1892fe52..e27b9eda7 100644
--- a/gui/projectfile.cpp
+++ b/gui/projectfile.cpp
@@ -26,7 +26,6 @@
 #include "common.h"
 #include "importproject.h"
 
-#include "path.h"
 #include "settings.h"
 
 ProjectFile::ProjectFile(QObject *parent) :
diff --git a/gui/report.h b/gui/report.h
index 99184f376..b5f7e1146 100644
--- a/gui/report.h
+++ b/gui/report.h
@@ -22,7 +22,8 @@
 #include <QObject>
 #include <QString>
 #include <QFile>
-#include "erroritem.h"
+
+class ErrorItem;
 
 /// @addtogroup GUI
 /// @{
diff --git a/gui/txtreport.cpp b/gui/txtreport.cpp
index cbf25f1ea..bb78d5595 100644
--- a/gui/txtreport.cpp
+++ b/gui/txtreport.cpp
@@ -17,6 +17,7 @@
  */
 
 #include <QDir>
+#include "erroritem.h"
 #include "txtreport.h"
 
 TxtReport::TxtReport(const QString &filename) :
diff --git a/gui/xmlreport.h b/gui/xmlreport.h
index 9e917b5f9..4da954eb8 100644
--- a/gui/xmlreport.h
+++ b/gui/xmlreport.h
@@ -22,8 +22,8 @@
 #include <QString>
 #include <QList>
 #include "report.h"
-#include "erroritem.h"
 
+class ErrorItem;
 class QObject;
 
 /// @addtogroup GUI
diff --git a/lib/astutils.h b/lib/astutils.h
index 396b773f3..7cd536a45 100644
--- a/lib/astutils.h
+++ b/lib/astutils.h
@@ -23,6 +23,7 @@
 //---------------------------------------------------------------------------
 
 #include <functional>
+#include <set>
 #include <string>
 #include <vector>
 
@@ -31,7 +32,6 @@
 
 class Library;
 class Settings;
-class Scope;
 class Token;
 class Variable;
 
diff --git a/lib/check.cpp b/lib/check.cpp
index 94d555dbf..5a1c92c92 100644
--- a/lib/check.cpp
+++ b/lib/check.cpp
@@ -19,6 +19,7 @@
 //---------------------------------------------------------------------------
 
 #include "check.h"
+#include "settings.h"
 
 #include <iostream>
 
diff --git a/lib/check.h b/lib/check.h
index 40306c249..e8e4fd026 100644
--- a/lib/check.h
+++ b/lib/check.h
@@ -22,11 +22,8 @@
 //---------------------------------------------------------------------------
 
 #include "config.h"
-#include "errorlogger.h"
-#include "settings.h"
 #include "token.h"
 #include "tokenize.h"
-#include "valueflow.h"
 
 #include <list>
 #include <string>
@@ -39,6 +36,13 @@ namespace CTU {
     class FileInfo;
 }
 
+namespace ValueFlow {
+    class Value;
+}
+
+class Settings;
+class Token;
+
 /** Use WRONG_DATA in checkers to mark conditions that check that data is correct */
 #define WRONG_DATA(COND, TOK)  (wrongData((TOK), (COND), #COND))
 
@@ -110,10 +114,10 @@ public:
     }
 
     // Return true if an error is reported.
-    virtual bool analyseWholeProgram(const CTU::FileInfo *ctu, const std::list<FileInfo*> &fileInfo, const Settings& settings, ErrorLogger &errorLogger) {
+    virtual bool analyseWholeProgram(const CTU::FileInfo *ctu, const std::list<FileInfo*> &fileInfo, const Settings& /*settings*/, ErrorLogger &errorLogger) {
         (void)ctu;
         (void)fileInfo;
-        (void)settings;
+        //(void)settings;
         (void)errorLogger;
         return false;
     }
diff --git a/lib/checkautovariables.h b/lib/checkautovariables.h
index bda712422..5e479c523 100644
--- a/lib/checkautovariables.h
+++ b/lib/checkautovariables.h
@@ -24,10 +24,10 @@
 
 #include "check.h"
 #include "config.h"
+#include "errorlogger.h"
 
 #include <string>
 
-class ErrorLogger;
 class Settings;
 class Token;
 class Tokenizer;
diff --git a/lib/checkbool.cpp b/lib/checkbool.cpp
index d5649b112..16a1cb92d 100644
--- a/lib/checkbool.cpp
+++ b/lib/checkbool.cpp
@@ -27,7 +27,6 @@
 #include "symboldatabase.h"
 #include "token.h"
 #include "tokenize.h"
-#include "valueflow.h"
 
 #include <cstddef>
 #include <list>
diff --git a/lib/checkbufferoverrun.cpp b/lib/checkbufferoverrun.cpp
index 18345ac4d..e3bee8cab 100644
--- a/lib/checkbufferoverrun.cpp
+++ b/lib/checkbufferoverrun.cpp
@@ -29,7 +29,6 @@
 #include "symboldatabase.h"
 #include "token.h"
 #include "tokenize.h"
-#include "tokenlist.h"
 #include "utils.h"
 #include "valueflow.h"
 
@@ -38,8 +37,6 @@
 #include <cstdlib>
 #include <numeric> // std::accumulate
 #include <sstream>
-#include <stack>
-#include <utility>
 
 //---------------------------------------------------------------------------
 
diff --git a/lib/checkbufferoverrun.h b/lib/checkbufferoverrun.h
index 386aad59e..494dcf7c6 100644
--- a/lib/checkbufferoverrun.h
+++ b/lib/checkbufferoverrun.h
@@ -25,10 +25,9 @@
 #include "check.h"
 #include "config.h"
 #include "ctu.h"
-#include "errorlogger.h"
 #include "mathlib.h"
-#include "tokenize.h"
 #include "symboldatabase.h"
+#include "valueflow.h"
 
 #include <cstddef>
 #include <list>
@@ -36,6 +35,14 @@
 #include <string>
 #include <vector>
 
+namespace tinyxml2 {
+	class XMLElement;
+}
+
+class ErrorLogger;
+class Settings;
+class Token;
+class Tokenizer;
 
 /// @addtogroup Checks
 /// @{
diff --git a/lib/checkclass.cpp b/lib/checkclass.cpp
index 399a83e8f..bacbbed3b 100644
--- a/lib/checkclass.cpp
+++ b/lib/checkclass.cpp
@@ -31,7 +31,6 @@
 
 #include <algorithm>
 #include <cstdlib>
-#include <stack>
 #include <utility>
 //---------------------------------------------------------------------------
 
diff --git a/lib/checkcondition.h b/lib/checkcondition.h
index bcadceb20..bcb9bb966 100644
--- a/lib/checkcondition.h
+++ b/lib/checkcondition.h
@@ -24,11 +24,11 @@
 
 #include "check.h"
 #include "config.h"
+#include "errorlogger.h"
 #include "mathlib.h"
 
 #include <string>
 
-class ErrorLogger;
 class Settings;
 class Token;
 class Tokenizer;
diff --git a/lib/checkexceptionsafety.h b/lib/checkexceptionsafety.h
index 76884b61a..30ed6339a 100644
--- a/lib/checkexceptionsafety.h
+++ b/lib/checkexceptionsafety.h
@@ -26,7 +26,6 @@
 #include "errorlogger.h"
 #include "token.h"
 #include "tokenize.h"
-#include "utils.h"
 
 #include <list>
 #include <string>
diff --git a/lib/checkinternal.cpp b/lib/checkinternal.cpp
index e7848c351..01faafa61 100644
--- a/lib/checkinternal.cpp
+++ b/lib/checkinternal.cpp
@@ -21,8 +21,10 @@
 #include "checkinternal.h"
 
 #include "astutils.h"
+#include "errorlogger.h"
 #include "symboldatabase.h"
-#include "utils.h"
+#include "token.h"
+#include "tokenize.h"
 
 #include <set>
 #include <cstring>
diff --git a/lib/checkinternal.h b/lib/checkinternal.h
index 28d0800bc..7eee138a8 100644
--- a/lib/checkinternal.h
+++ b/lib/checkinternal.h
@@ -24,6 +24,7 @@
 
 #include "check.h"
 #include "config.h"
+#include "settings.h"
 
 #include <string>
 
diff --git a/lib/checkleakautovar.cpp b/lib/checkleakautovar.cpp
index 4ea5c7396..d19bcda13 100644
--- a/lib/checkleakautovar.cpp
+++ b/lib/checkleakautovar.cpp
@@ -31,7 +31,6 @@
 #include "symboldatabase.h"
 #include "token.h"
 #include "tokenize.h"
-#include "valueflow.h"
 
 #include <cstddef>
 #include <iostream>
diff --git a/lib/checkmemoryleak.cpp b/lib/checkmemoryleak.cpp
index acb4e14c3..a76656b4a 100644
--- a/lib/checkmemoryleak.cpp
+++ b/lib/checkmemoryleak.cpp
@@ -21,20 +21,15 @@
 
 #include "astutils.h"
 #include "library.h"
-#include "mathlib.h"
 #include "settings.h"
-#include "standards.h"
 #include "symboldatabase.h"
 #include "token.h"
 #include "tokenize.h"
-#include "tokenlist.h"
 #include "utils.h"
-#include "valueflow.h"
 
 #include <algorithm>
 #include <cstddef>
 #include <set>
-#include <stack>
 
 //---------------------------------------------------------------------------
 
diff --git a/lib/checkmemoryleak.h b/lib/checkmemoryleak.h
index 424c7263b..d66dd76c7 100644
--- a/lib/checkmemoryleak.h
+++ b/lib/checkmemoryleak.h
@@ -43,7 +43,6 @@
 class Function;
 class Scope;
 class Settings;
-class SymbolDatabase;
 class Token;
 class Variable;
 
diff --git a/lib/checknullpointer.cpp b/lib/checknullpointer.cpp
index 5cb202d50..4ed9a6eb9 100644
--- a/lib/checknullpointer.cpp
+++ b/lib/checknullpointer.cpp
@@ -23,11 +23,11 @@
 #include "astutils.h"
 #include "errorlogger.h"
 #include "library.h"
+#include "mathlib.h"
 #include "settings.h"
 #include "symboldatabase.h"
 #include "token.h"
 #include "tokenize.h"
-#include "utils.h"
 
 #include <algorithm>
 #include <cctype>
diff --git a/lib/checkother.cpp b/lib/checkother.cpp
index 7a6b5d343..ac9d85d32 100644
--- a/lib/checkother.cpp
+++ b/lib/checkother.cpp
@@ -36,7 +36,6 @@
 #include <list>
 #include <map>
 #include <ostream>
-#include <set>
 #include <utility>
 //---------------------------------------------------------------------------
 
diff --git a/lib/checkother.h b/lib/checkother.h
index 0028c5a39..6fa4e7d92 100644
--- a/lib/checkother.h
+++ b/lib/checkother.h
@@ -24,13 +24,17 @@
 
 #include "check.h"
 #include "config.h"
-#include "valueflow.h"
+#include "errorlogger.h"
+#include "utils.h"
 
 #include <cstddef>
 #include <string>
 #include <vector>
 
-class ErrorLogger;
+namespace ValueFlow {
+    class Value;
+}
+
 class Settings;
 class Token;
 class Tokenizer;
diff --git a/lib/checkstl.cpp b/lib/checkstl.cpp
index 9fe1f643f..090fa9963 100644
--- a/lib/checkstl.cpp
+++ b/lib/checkstl.cpp
@@ -18,8 +18,9 @@
 
 #include "checkstl.h"
 
-#include "checknullpointer.h"
 #include "errorlogger.h"
+#include "library.h"
+#include "mathlib.h"
 #include "settings.h"
 #include "standards.h"
 #include "symboldatabase.h"
diff --git a/lib/checkstl.h b/lib/checkstl.h
index 41b002392..e0d3ec800 100644
--- a/lib/checkstl.h
+++ b/lib/checkstl.h
@@ -24,13 +24,13 @@
 
 #include "check.h"
 #include "config.h"
-#include "library.h"
+#include "errorlogger.h"
 #include "tokenize.h"
+#include "utils.h"
+#include "valueflow.h"
 
-#include <map>
 #include <string>
 
-class ErrorLogger;
 class Scope;
 class Settings;
 class Token;
diff --git a/lib/checkuninitvar.cpp b/lib/checkuninitvar.cpp
index 4b56f1e32..62f81be6c 100644
--- a/lib/checkuninitvar.cpp
+++ b/lib/checkuninitvar.cpp
@@ -31,14 +31,18 @@
 #include "tokenize.h"
 #include "valueflow.h"
 
-#include <tinyxml2.h>
-
 #include <cassert>
 #include <cstddef>
 #include <list>
 #include <map>
 #include <stack>
 #include <utility>
+
+
+namespace tinyxml2 {
+    class XMLElement;
+}
+
 //---------------------------------------------------------------------------
 
 // Register this check class (by creating a static instance of it)
diff --git a/lib/checkuninitvar.h b/lib/checkuninitvar.h
index d10dd9a14..33a053ec9 100644
--- a/lib/checkuninitvar.h
+++ b/lib/checkuninitvar.h
@@ -25,13 +25,15 @@
 #include "check.h"
 #include "config.h"
 #include "ctu.h"
+#include "errorlogger.h"
+#include "mathlib.h"
+#include "settings.h"
+#include "utils.h"
 
 #include <set>
 #include <string>
 
-class ErrorLogger;
 class Scope;
-class Settings;
 class Token;
 class Tokenizer;
 class Variable;
diff --git a/lib/cppcheck.cpp b/lib/cppcheck.cpp
index 0206afb96..c41043be6 100644
--- a/lib/cppcheck.cpp
+++ b/lib/cppcheck.cpp
@@ -28,7 +28,6 @@
 #include "preprocessor.h" // Preprocessor
 #include "suppressions.h"
 #include "timer.h"
-#include "token.h"
 #include "tokenize.h" // Tokenizer
 #include "tokenlist.h"
 #include "version.h"
diff --git a/lib/ctu.cpp b/lib/ctu.cpp
index 8313cb66a..9cfb566ab 100644
--- a/lib/ctu.cpp
+++ b/lib/ctu.cpp
@@ -20,6 +20,7 @@
 //---------------------------------------------------------------------------
 #include "ctu.h"
 #include "astutils.h"
+#include "settings.h"
 #include "symboldatabase.h"
 #include <tinyxml2.h>
 #include <iterator>  // back_inserter
diff --git a/lib/exprengine.h b/lib/exprengine.h
index 44da3f1d2..24cdd7b6c 100644
--- a/lib/exprengine.h
+++ b/lib/exprengine.h
@@ -26,10 +26,9 @@
 #include <functional>
 #include <map>
 #include <memory>
-#include <set>
 #include <string>
 #include <vector>
-#include <stdint.h>
+#include <cstdint>
 
 class ErrorLogger;
 class Tokenizer;
diff --git a/lib/forwardanalyzer.cpp b/lib/forwardanalyzer.cpp
index 49bc5aeed..84ec6eddc 100644
--- a/lib/forwardanalyzer.cpp
+++ b/lib/forwardanalyzer.cpp
@@ -3,6 +3,7 @@
 #include "settings.h"
 #include "symboldatabase.h"
 #include "token.h"
+#include "valueptr.h"
 
 #include <functional>
 
diff --git a/lib/forwardanalyzer.h b/lib/forwardanalyzer.h
index 908f898a9..4d49f2ffd 100644
--- a/lib/forwardanalyzer.h
+++ b/lib/forwardanalyzer.h
@@ -19,11 +19,11 @@
 #ifndef forwardanalyzerH
 #define forwardanalyzerH
 
-#include "token.h"
 #include "valueptr.h"
 #include <vector>
 
 class Settings;
+class Token;
 
 struct ForwardAnalyzer {
     struct Action {
diff --git a/lib/importproject.cpp b/lib/importproject.cpp
index 056c2cbc2..b99f71d48 100644
--- a/lib/importproject.cpp
+++ b/lib/importproject.cpp
@@ -20,10 +20,10 @@
 
 #include "path.h"
 #include "settings.h"
+#include "suppressions.h"
 #include "tinyxml2.h"
 #include "token.h"
 #include "tokenize.h"
-#include "tokenlist.h"
 #include "utils.h"
 #define PICOJSON_USE_INT64
 #include <picojson.h>
diff --git a/lib/pathanalysis.cpp b/lib/pathanalysis.cpp
index 583430536..c8ecc2a68 100644
--- a/lib/pathanalysis.cpp
+++ b/lib/pathanalysis.cpp
@@ -1,10 +1,8 @@
 #include "pathanalysis.h"
 #include "astutils.h"
-#include "library.h"
-#include "mathlib.h"
-#include "settings.h"
 #include "symboldatabase.h"
 #include "token.h"
+#include "valueflow.h"
 
 const Scope* PathAnalysis::findOuterScope(const Scope * scope)
 {
diff --git a/lib/pathanalysis.h b/lib/pathanalysis.h
index 126a6de60..6efc76d83 100644
--- a/lib/pathanalysis.h
+++ b/lib/pathanalysis.h
@@ -4,10 +4,8 @@
 #include <functional>
 
 #include "errorlogger.h"
-#include "utils.h"
 
 class Library;
-class Settings;
 class Scope;
 class Token;
 
diff --git a/lib/programmemory.h b/lib/programmemory.h
index 2877f455e..68df1db4a 100644
--- a/lib/programmemory.h
+++ b/lib/programmemory.h
@@ -1,13 +1,14 @@
 #ifndef GUARD_PROGRAMMEMORY_H
 #define GUARD_PROGRAMMEMORY_H
 
-#include "config.h"
 #include "utils.h"
 #include "valueflow.h"
 #include "mathlib.h"
 #include <map>
 #include <unordered_map>
 
+class Token;
+
 struct ProgramMemory {
     using Map = std::unordered_map<nonneg int, ValueFlow::Value>;
     Map values;
diff --git a/lib/suppressions.cpp b/lib/suppressions.cpp
index 3ed9ee777..854fea173 100644
--- a/lib/suppressions.cpp
+++ b/lib/suppressions.cpp
@@ -30,8 +30,6 @@
 #include <sstream>
 #include <utility>
 
-class ErrorLogger;
-
 static bool isAcceptedErrorIdChar(char c)
 {
     switch (c) {
diff --git a/lib/suppressions.h b/lib/suppressions.h
index ca4c4855f..a07ae3cc4 100644
--- a/lib/suppressions.h
+++ b/lib/suppressions.h
@@ -24,7 +24,6 @@
 
 #include <istream>
 #include <list>
-#include <set>
 #include <string>
 #include <vector>
 
diff --git a/lib/symboldatabase.h b/lib/symboldatabase.h
index 2d634af7a..03f8e0b04 100644
--- a/lib/symboldatabase.h
+++ b/lib/symboldatabase.h
@@ -24,8 +24,8 @@
 #include "config.h"
 #include "library.h"
 #include "mathlib.h"
-#include "platform.h"
 #include "token.h"
+#include "utils.h"
 
 #include <cstddef>
 #include <list>
@@ -35,6 +35,10 @@
 #include <utility>
 #include <vector>
 
+namespace cppcheck {
+    class Platform;
+}
+
 class ErrorLogger;
 class Function;
 class Scope;
diff --git a/lib/tokenize.cpp b/lib/tokenize.cpp
index 7bd0daa71..4583c881d 100644
--- a/lib/tokenize.cpp
+++ b/lib/tokenize.cpp
@@ -22,7 +22,6 @@
 #include "check.h"
 #include "library.h"
 #include "mathlib.h"
-#include "path.h"
 #include "platform.h"
 #include "settings.h"
 #include "standards.h"
diff --git a/lib/tokenlist.cpp b/lib/tokenlist.cpp
index f442e7e2b..81608d0f2 100644
--- a/lib/tokenlist.cpp
+++ b/lib/tokenlist.cpp
@@ -20,9 +20,10 @@
 #include "tokenlist.h"
 
 #include "errorlogger.h"
-#include "mathlib.h"
+#include "library.h"
 #include "path.h"
 #include "settings.h"
+#include "standards.h"
 #include "token.h"
 
 #include <simplecpp.h>
diff --git a/lib/tokenlist.h b/lib/tokenlist.h
index 9ef144c9f..9ee65eecf 100644
--- a/lib/tokenlist.h
+++ b/lib/tokenlist.h
@@ -28,7 +28,6 @@
 #include <vector>
 
 class Settings;
-class Token;
 
 namespace simplecpp {
     class TokenList;
diff --git a/test/testbufferoverrun.cpp b/test/testbufferoverrun.cpp
index 9013d219c..6d96fe312 100644
--- a/test/testbufferoverrun.cpp
+++ b/test/testbufferoverrun.cpp
@@ -17,11 +17,13 @@
  */
 
 
+#include "check.h"
 #include "checkbufferoverrun.h"
+#include "config.h"
+#include "ctu.h"
 #include "library.h"
 #include "settings.h"
 #include "testsuite.h"
-#include "token.h"
 #include "tokenize.h"
 
 #include <tinyxml2.h>
diff --git a/test/testexprengine.cpp b/test/testexprengine.cpp
index 829875a0e..d5b1703ad 100644
--- a/test/testexprengine.cpp
+++ b/test/testexprengine.cpp
@@ -16,9 +16,12 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include "config.h"
 #include "exprengine.h"
+#include "library.h"
+#include "platform.h"
 #include "settings.h"
-#include "symboldatabase.h"
+#include "token.h"
 #include "tokenize.h"
 #include "testsuite.h"
 
diff --git a/test/testmemleak.cpp b/test/testmemleak.cpp
index 40cecbaec..6a88cd302 100644
--- a/test/testmemleak.cpp
+++ b/test/testmemleak.cpp
@@ -16,22 +16,16 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 #include "checkmemoryleak.h"
-#include "preprocessor.h"
+#include "config.h"
 #include "settings.h"
-#include "simplecpp.h"
-#include "standards.h"
 #include "symboldatabase.h"
 #include "testsuite.h"
 #include "token.h"
 #include "tokenize.h"
-#include "tokenlist.h"
 
 #include <list>
 #include <ostream>
 #include <string>
-#include <vector>
-
-struct InternalError;
 
 
 class TestMemleak : private TestFixture {
diff --git a/test/testnullpointer.cpp b/test/testnullpointer.cpp
index 92bb85c92..bed036f28 100644
--- a/test/testnullpointer.cpp
+++ b/test/testnullpointer.cpp
@@ -16,8 +16,10 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include "check.h"
 #include "checknullpointer.h"
-#include "checkuninitvar.h"
+#include "config.h"
+#include "ctu.h"
 #include "library.h"
 #include "settings.h"
 #include "testsuite.h"
@@ -25,7 +27,6 @@
 #include "tokenize.h"
 
 #include <simplecpp.h>
-#include <tinyxml2.h>
 #include <list>
 #include <map>
 #include <string>
diff --git a/test/testplatform.cpp b/test/testplatform.cpp
index 27ca7bb62..b60b7a0fe 100644
--- a/test/testplatform.cpp
+++ b/test/testplatform.cpp
@@ -16,7 +16,7 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include "errorlogger.h"
+#include "config.h"
 #include "platform.h"
 #include "testsuite.h"
 
diff --git a/test/testsamples.cpp b/test/testsamples.cpp
index 19db64b6a..d395be6cf 100644
--- a/test/testsamples.cpp
+++ b/test/testsamples.cpp
@@ -16,13 +16,14 @@
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
+#include "config.h"
 #include "cppcheckexecutor.h"
 #include "errorlogger.h"
-#include "cppcheck.h"
 #include "filelister.h"
 #include "path.h"
 #include "pathmatch.h"
 #include "redirect.h"
+#include "settings.h"
 #include "testsuite.h"
 
 #include <algorithm>
diff --git a/test/testsimplifyusing.cpp b/test/testsimplifyusing.cpp
index 02011c0d8..e82598dcd 100644
--- a/test/testsimplifyusing.cpp
+++ b/test/testsimplifyusing.cpp
@@ -17,12 +17,12 @@
  */
 
 
+#include "config.h"
 #include "platform.h"
 #include "settings.h"
 #include "testsuite.h"
 #include "token.h"
 #include "tokenize.h"
-#include "tokenlist.h"
 
 struct InternalError;
 
diff --git a/test/testsuppressions.cpp b/test/testsuppressions.cpp
index 63a9266aa..eed41391b 100644
--- a/test/testsuppressions.cpp
+++ b/test/testsuppressions.cpp
@@ -22,7 +22,6 @@
 #include "suppressions.h"
 #include "testsuite.h"
 #include "threadexecutor.h"
-#include "path.h"
 
 #include <cstddef>
 #include <list>
diff --git a/test/testsymboldatabase.cpp b/test/testsymboldatabase.cpp
index daa561bf5..4952388fb 100644
--- a/test/testsymboldatabase.cpp
+++ b/test/testsymboldatabase.cpp
@@ -16,6 +16,8 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include "config.h"
+#include "library.h"
 #include "platform.h"
 #include "settings.h"
 #include "symboldatabase.h"
@@ -24,7 +26,6 @@
 #include "token.h"
 #include "tokenize.h"
 #include "tokenlist.h"
-#include "utils.h"
 
 #include <climits>
 #include <cstddef>