diff --git a/cli/cmdlineparser.h b/cli/cmdlineparser.h
index f7d240b55cc..fcdd2157ecc 100644
--- a/cli/cmdlineparser.h
+++ b/cli/cmdlineparser.h
@@ -22,7 +22,6 @@
 #include <cstddef>
 #include <list>
 #include <string>
-#include <utility>
 #include <vector>
 
 #include "cmdlinelogger.h"
diff --git a/cli/cppcheckexecutor.h b/cli/cppcheckexecutor.h
index 86d938c58b9..8a740cffee0 100644
--- a/cli/cppcheckexecutor.h
+++ b/cli/cppcheckexecutor.h
@@ -25,13 +25,11 @@
 #include <cstdio>
 #include <list>
 #include <string>
-#include <utility>
 #include <vector>
 
 class Settings;
 class ErrorLogger;
 class SuppressionList;
-class FileWithDetails;
 
 /**
  * This class works as an example of how CppCheck can be used in external
diff --git a/cli/filelister.cpp b/cli/filelister.cpp
index a960f592fb0..98bb6e855b5 100644
--- a/cli/filelister.cpp
+++ b/cli/filelister.cpp
@@ -23,7 +23,6 @@
 #include "pathmatch.h"
 #include "utils.h"
 
-#include <cstddef>
 #include <cstring>
 #include <iterator>
 #include <memory>
diff --git a/cli/filelister.h b/cli/filelister.h
index 81f6d6ff8fa..92479a730e5 100644
--- a/cli/filelister.h
+++ b/cli/filelister.h
@@ -19,11 +19,9 @@
 #ifndef filelisterH
 #define filelisterH
 
-#include <cstddef>
 #include <list>
 #include <set>
 #include <string>
-#include <utility>
 
 class PathMatch;
 class FileWithDetails;
diff --git a/cli/processexecutor.h b/cli/processexecutor.h
index 9e94557c5b8..675b7c429b9 100644
--- a/cli/processexecutor.h
+++ b/cli/processexecutor.h
@@ -25,7 +25,6 @@
 #include <cstddef>
 #include <list>
 #include <string>
-#include <utility>
 
 class Settings;
 class ErrorLogger;
diff --git a/cli/singleexecutor.cpp b/cli/singleexecutor.cpp
index da3e0fcc34a..9979a7baa4c 100644
--- a/cli/singleexecutor.cpp
+++ b/cli/singleexecutor.cpp
@@ -24,9 +24,9 @@
 #include "timer.h"
 
 #include <cassert>
+#include <cstddef>
 #include <list>
 #include <numeric>
-#include <utility>
 
 class ErrorLogger;
 
diff --git a/cli/threadexecutor.cpp b/cli/threadexecutor.cpp
index 4525166d508..ea96d8dfc85 100644
--- a/cli/threadexecutor.cpp
+++ b/cli/threadexecutor.cpp
@@ -25,14 +25,15 @@
 #include "settings.h"
 #include "timer.h"
 
-#include <algorithm>
 #include <cassert>
+#include <cstddef>
 #include <cstdlib>
 #include <future>
 #include <iostream>
 #include <list>
 #include <numeric>
 #include <mutex>
+#include <string>
 #include <system_error>
 #include <utility>
 #include <vector>
diff --git a/cli/threadexecutor.h b/cli/threadexecutor.h
index c2233783951..1706cfffa4d 100644
--- a/cli/threadexecutor.h
+++ b/cli/threadexecutor.h
@@ -22,10 +22,7 @@
 #include "cppcheck.h"
 #include "executor.h"
 
-#include <cstddef>
 #include <list>
-#include <string>
-#include <utility>
 
 class Settings;
 class ErrorLogger;
diff --git a/gui/resultstree.cpp b/gui/resultstree.cpp
index 2ee74f67e44..a822be0b3d1 100644
--- a/gui/resultstree.cpp
+++ b/gui/resultstree.cpp
@@ -21,7 +21,6 @@
 #include "application.h"
 #include "applicationlist.h"
 #include "common.h"
-#include "config.h"
 #include "erroritem.h"
 #include "errorlogger.h"
 #include "errortypes.h"
diff --git a/lib/checkassert.cpp b/lib/checkassert.cpp
index b6ad58b3510..26d0c93b8cc 100644
--- a/lib/checkassert.cpp
+++ b/lib/checkassert.cpp
@@ -24,12 +24,16 @@
 
 #include "astutils.h"
 #include "errortypes.h"
+#include "library.h"
 #include "settings.h"
 #include "symboldatabase.h"
 #include "token.h"
 #include "tokenize.h"
 #include "tokenlist.h"
 
+#include <algorithm>
+#include <utility>
+
 //---------------------------------------------------------------------------
 
 // CWE ids used
diff --git a/lib/checkstl.cpp b/lib/checkstl.cpp
index 54da256288c..07453a26f49 100644
--- a/lib/checkstl.cpp
+++ b/lib/checkstl.cpp
@@ -34,7 +34,6 @@
 #include "checknullpointer.h"
 
 #include <algorithm>
-#include <cassert>
 #include <iterator>
 #include <list>
 #include <map>
diff --git a/lib/tokenize.h b/lib/tokenize.h
index 801cae8637c..c1145a3c781 100644
--- a/lib/tokenize.h
+++ b/lib/tokenize.h
@@ -36,7 +36,7 @@ class TimerResults;
 class Token;
 class TemplateSimplifier;
 class ErrorLogger;
-struct Directive; // IWYU pragma: keep
+struct Directive;
 enum class Severity;
 
 /// @addtogroup Core
diff --git a/test/test64bit.cpp b/test/test64bit.cpp
index 0b04ee6146a..a33df481384 100644
--- a/test/test64bit.cpp
+++ b/test/test64bit.cpp
@@ -22,6 +22,8 @@
 #include "helpers.h"
 #include "settings.h"
 
+#include <cstddef>
+
 class Test64BitPortability : public TestFixture {
 public:
     Test64BitPortability() : TestFixture("Test64BitPortability") {}
diff --git a/test/testastutils.cpp b/test/testastutils.cpp
index 01d66d01614..8ec39c4eb35 100644
--- a/test/testastutils.cpp
+++ b/test/testastutils.cpp
@@ -19,7 +19,6 @@
 #include "astutils.h"
 #include "fixture.h"
 #include "helpers.h"
-#include "library.h"
 #include "settings.h"
 #include "symboldatabase.h"
 #include "token.h"
diff --git a/test/testautovariables.cpp b/test/testautovariables.cpp
index dabc9ec3380..80205c2f9b6 100644
--- a/test/testautovariables.cpp
+++ b/test/testautovariables.cpp
@@ -22,6 +22,8 @@
 #include "helpers.h"
 #include "settings.h"
 
+#include <cstddef>
+
 class TestAutoVariables : public TestFixture {
 public:
     TestAutoVariables() : TestFixture("TestAutoVariables") {}
diff --git a/test/testbool.cpp b/test/testbool.cpp
index f1de81d942e..a6cf31dd832 100644
--- a/test/testbool.cpp
+++ b/test/testbool.cpp
@@ -22,6 +22,8 @@
 #include "helpers.h"
 #include "settings.h"
 
+#include <cstddef>
+
 class TestBool : public TestFixture {
 public:
     TestBool() : TestFixture("TestBool") {}
diff --git a/test/testboost.cpp b/test/testboost.cpp
index b52d5c7330d..ff8b2a44655 100644
--- a/test/testboost.cpp
+++ b/test/testboost.cpp
@@ -22,6 +22,8 @@
 #include "helpers.h"
 #include "settings.h"
 
+#include <cstddef>
+
 class TestBoost : public TestFixture {
 public:
     TestBoost() : TestFixture("TestBoost") {}
diff --git a/test/testbufferoverrun.cpp b/test/testbufferoverrun.cpp
index f0ee3128010..7d557c8b85b 100644
--- a/test/testbufferoverrun.cpp
+++ b/test/testbufferoverrun.cpp
@@ -28,6 +28,7 @@
 #include "fixture.h"
 #include "tokenize.h"
 
+#include <cstddef>
 #include <list>
 #include <string>
 #include <vector>
diff --git a/test/testcharvar.cpp b/test/testcharvar.cpp
index bbb10b81218..dcbe49cca26 100644
--- a/test/testcharvar.cpp
+++ b/test/testcharvar.cpp
@@ -23,6 +23,8 @@
 #include "platform.h"
 #include "settings.h"
 
+#include <cstddef>
+
 class TestCharVar : public TestFixture {
 public:
     TestCharVar() : TestFixture("TestCharVar") {}
diff --git a/test/testclass.cpp b/test/testclass.cpp
index f8713702e41..00408e24993 100644
--- a/test/testclass.cpp
+++ b/test/testclass.cpp
@@ -25,6 +25,7 @@
 #include "tokenize.h"
 #include "tokenlist.h"
 
+#include <cstddef>
 #include <list>
 #include <sstream>
 #include <string>
diff --git a/test/testcondition.cpp b/test/testcondition.cpp
index 8005c400e50..2f634d843fd 100644
--- a/test/testcondition.cpp
+++ b/test/testcondition.cpp
@@ -24,6 +24,7 @@
 #include "settings.h"
 #include "tokenize.h"
 
+#include <cstddef>
 #include <limits>
 #include <string>
 #include <vector>
diff --git a/test/testconstructors.cpp b/test/testconstructors.cpp
index 6b265f6fe84..28cbf206711 100644
--- a/test/testconstructors.cpp
+++ b/test/testconstructors.cpp
@@ -23,6 +23,8 @@
 #include "standards.h"
 #include "settings.h"
 
+#include <cstddef>
+
 class TestConstructors : public TestFixture {
 public:
     TestConstructors() : TestFixture("TestConstructors") {}
diff --git a/test/testexceptionsafety.cpp b/test/testexceptionsafety.cpp
index 9e10e1e2290..03f7c6a6815 100644
--- a/test/testexceptionsafety.cpp
+++ b/test/testexceptionsafety.cpp
@@ -22,6 +22,8 @@
 #include "helpers.h"
 #include "settings.h"
 
+#include <cstddef>
+
 class TestExceptionSafety : public TestFixture {
 public:
     TestExceptionSafety() : TestFixture("TestExceptionSafety") {}
diff --git a/test/testfilelister.cpp b/test/testfilelister.cpp
index 7eb5bb4e09b..092ac86a3b6 100644
--- a/test/testfilelister.cpp
+++ b/test/testfilelister.cpp
@@ -23,7 +23,6 @@
 #include "fixture.h"
 
 #include <algorithm>
-#include <cstddef>
 #include <list>
 #include <stdexcept>
 #include <string>
diff --git a/test/testfunctions.cpp b/test/testfunctions.cpp
index b622207f1e2..a6758087622 100644
--- a/test/testfunctions.cpp
+++ b/test/testfunctions.cpp
@@ -23,6 +23,7 @@
 #include "settings.h"
 #include "standards.h"
 
+#include <cstddef>
 #include <string>
 
 class TestFunctions : public TestFixture {
diff --git a/test/testgarbage.cpp b/test/testgarbage.cpp
index 93b2d12ee78..f022b64ac61 100644
--- a/test/testgarbage.cpp
+++ b/test/testgarbage.cpp
@@ -23,6 +23,7 @@
 #include "settings.h"
 #include "token.h"
 
+#include <cstddef>
 #include <list>
 #include <string>
 
diff --git a/test/testinternal.cpp b/test/testinternal.cpp
index 519e1aca892..5dc59aad9f4 100644
--- a/test/testinternal.cpp
+++ b/test/testinternal.cpp
@@ -23,6 +23,8 @@
 #include "helpers.h"
 #include "settings.h"
 
+#include <cstddef>
+
 class TestInternal : public TestFixture {
 public:
     TestInternal() : TestFixture("TestInternal") {}
diff --git a/test/testio.cpp b/test/testio.cpp
index 5c70a4deac8..0f21343ff16 100644
--- a/test/testio.cpp
+++ b/test/testio.cpp
@@ -24,6 +24,7 @@
 #include "platform.h"
 #include "settings.h"
 
+#include <cstddef>
 #include <string>
 
 class TestIO : public TestFixture {
diff --git a/test/testmemleak.cpp b/test/testmemleak.cpp
index a9c8c34c465..b6be95bd8be 100644
--- a/test/testmemleak.cpp
+++ b/test/testmemleak.cpp
@@ -24,6 +24,7 @@
 #include "symboldatabase.h"
 #include "token.h"
 
+#include <cstddef>
 #include <list>
 
 class TestMemleak : private TestFixture {
diff --git a/test/testnullpointer.cpp b/test/testnullpointer.cpp
index e2bf2c82dc3..05502dbf980 100644
--- a/test/testnullpointer.cpp
+++ b/test/testnullpointer.cpp
@@ -27,6 +27,7 @@
 #include "token.h"
 #include "tokenize.h"
 
+#include <cstddef>
 #include <list>
 #include <map>
 #include <string>
diff --git a/test/testother.cpp b/test/testother.cpp
index 9b9584cd3dd..ff151fdad05 100644
--- a/test/testother.cpp
+++ b/test/testother.cpp
@@ -25,6 +25,7 @@
 #include "standards.h"
 #include "tokenize.h"
 
+#include <cstddef>
 #include <string>
 #include <vector>
 
diff --git a/test/testpostfixoperator.cpp b/test/testpostfixoperator.cpp
index b33f33b5e41..d2d3dbf84a8 100644
--- a/test/testpostfixoperator.cpp
+++ b/test/testpostfixoperator.cpp
@@ -22,6 +22,8 @@
 #include "helpers.h"
 #include "settings.h"
 
+#include <cstddef>
+
 class TestPostfixOperator : public TestFixture {
 public:
     TestPostfixOperator() : TestFixture("TestPostfixOperator") {}
diff --git a/test/testsimplifytokens.cpp b/test/testsimplifytokens.cpp
index 6af24e798af..b034e617a9e 100644
--- a/test/testsimplifytokens.cpp
+++ b/test/testsimplifytokens.cpp
@@ -24,9 +24,9 @@
 #include "fixture.h"
 #include "token.h"
 
+#include <cstddef>
 #include <string>
 
-
 class TestSimplifyTokens : public TestFixture {
 public:
     TestSimplifyTokens() : TestFixture("TestSimplifyTokens") {}
diff --git a/test/testsimplifyusing.cpp b/test/testsimplifyusing.cpp
index e39214e88ab..9cc79f6eb6a 100644
--- a/test/testsimplifyusing.cpp
+++ b/test/testsimplifyusing.cpp
@@ -26,6 +26,7 @@
 #include "tokenlist.h"
 #include "utils.h"
 
+#include <cstddef>
 #include <sstream>
 #include <string>
 #include <vector>
diff --git a/test/testsizeof.cpp b/test/testsizeof.cpp
index ba11c1ff6af..f0e05c8de44 100644
--- a/test/testsizeof.cpp
+++ b/test/testsizeof.cpp
@@ -23,6 +23,7 @@
 #include "settings.h"
 #include "tokenize.h"
 
+#include <cstddef>
 #include <string>
 #include <vector>
 
diff --git a/test/testsummaries.cpp b/test/testsummaries.cpp
index fde4e51f5a8..8939731f95b 100644
--- a/test/testsummaries.cpp
+++ b/test/testsummaries.cpp
@@ -20,6 +20,7 @@
 #include "helpers.h"
 #include "summaries.h"
 
+#include <cstddef>
 #include <string>
 
 class TestSummaries : public TestFixture {
diff --git a/test/testsuppressions.cpp b/test/testsuppressions.cpp
index 5e31520ce96..d2dcfb26eac 100644
--- a/test/testsuppressions.cpp
+++ b/test/testsuppressions.cpp
@@ -29,7 +29,6 @@
 #include "threadexecutor.h"
 #include "singleexecutor.h"
 
-#include <cstddef>
 #include <cstring>
 #include <list>
 #include <map>
diff --git a/test/testtokenlist.cpp b/test/testtokenlist.cpp
index ec4058cfe9c..80b16002482 100644
--- a/test/testtokenlist.cpp
+++ b/test/testtokenlist.cpp
@@ -28,6 +28,8 @@
 #include <sstream>
 #include <stack>
 #include <string>
+#include <utility>
+#include <vector>
 
 #include <simplecpp.h>
 
diff --git a/test/testtype.cpp b/test/testtype.cpp
index d00b52dd52d..fb9f6fee71a 100644
--- a/test/testtype.cpp
+++ b/test/testtype.cpp
@@ -25,6 +25,7 @@
 #include "standards.h"
 #include "tokenize.h"
 
+#include <cstddef>
 #include <list>
 #include <string>
 #include <vector>
diff --git a/test/testunusedfunctions.cpp b/test/testunusedfunctions.cpp
index f18f0953045..91f1c1e11bf 100644
--- a/test/testunusedfunctions.cpp
+++ b/test/testunusedfunctions.cpp
@@ -25,6 +25,7 @@
 #include "tokenize.h"
 #include "tokenlist.h"
 
+#include <cstddef>
 #include <sstream>
 #include <string>
 
diff --git a/test/testvaarg.cpp b/test/testvaarg.cpp
index aab291c405f..f4a42a4a111 100644
--- a/test/testvaarg.cpp
+++ b/test/testvaarg.cpp
@@ -22,6 +22,8 @@
 #include "helpers.h"
 #include "settings.h"
 
+#include <cstddef>
+
 class TestVaarg : public TestFixture {
 public:
     TestVaarg() : TestFixture("TestVaarg") {}
diff --git a/test/testvarid.cpp b/test/testvarid.cpp
index e35f9af0379..126cb791f44 100644
--- a/test/testvarid.cpp
+++ b/test/testvarid.cpp
@@ -25,6 +25,7 @@
 #include "tokenize.h"
 #include "tokenlist.h"
 
+#include <cstddef>
 #include <sstream>
 #include <string>
 #include <vector>