diff --git a/include/podio/CollectionBase.h b/include/podio/CollectionBase.h
index 2c0224557..85eebf392 100644
--- a/include/podio/CollectionBase.h
+++ b/include/podio/CollectionBase.h
@@ -2,13 +2,10 @@
 #define PODIO_COLLECTIONBASE_H
 
 #include "podio/CollectionBuffers.h"
-#include "podio/ObjectID.h"
 #include "podio/SchemaEvolution.h"
 
 #include <iostream>
 #include <string_view>
-#include <utility>
-#include <vector>
 
 namespace podio {
 // forward declarations
diff --git a/include/podio/RNTupleReader.h b/include/podio/RNTupleReader.h
index 057b9fcef..373e7c45f 100644
--- a/include/podio/RNTupleReader.h
+++ b/include/podio/RNTupleReader.h
@@ -12,7 +12,6 @@
 #include <vector>
 
 #include <ROOT/RNTuple.hxx>
-#include <ROOT/RNTupleModel.hxx>
 #include <RVersion.h>
 #if ROOT_VERSION_CODE >= ROOT_VERSION(6, 31, 0)
   #include <ROOT/RNTupleReader.hxx>
diff --git a/include/podio/RNTupleWriter.h b/include/podio/RNTupleWriter.h
index d8a53ba43..b57eb09b3 100644
--- a/include/podio/RNTupleWriter.h
+++ b/include/podio/RNTupleWriter.h
@@ -2,7 +2,6 @@
 #define PODIO_RNTUPLEWRITER_H
 
 #include "podio/Frame.h"
-#include "podio/GenericParameters.h"
 #include "podio/SchemaEvolution.h"
 #include "podio/utilities/DatamodelRegistryIOHelpers.h"
 #include "podio/utilities/RootHelpers.h"
@@ -10,7 +9,6 @@
 #include "TFile.h"
 #include <ROOT/RNTuple.hxx>
 #include <ROOT/RNTupleModel.hxx>
-#include <RVersion.h>
 #if ROOT_VERSION_CODE >= ROOT_VERSION(6, 31, 0)
   #include <ROOT/RNTupleWriter.hxx>
 #endif
diff --git a/include/podio/UserDataCollection.h b/include/podio/UserDataCollection.h
index 35407cddb..63660a72f 100644
--- a/include/podio/UserDataCollection.h
+++ b/include/podio/UserDataCollection.h
@@ -7,12 +7,6 @@
 #include "podio/SchemaEvolution.h"
 #include "podio/utilities/TypeHelpers.h"
 
-#include <map>
-#include <string>
-#include <typeindex>
-#include <utility>
-#include <vector>
-
 #define PODIO_ADD_USER_TYPE(type)                                                                                      \
   template <>                                                                                                          \
   constexpr const char* userDataTypeName<type>() {                                                                     \
diff --git a/src/GenericParameters.cc b/src/GenericParameters.cc
index f787cc931..f6aaf21c0 100644
--- a/src/GenericParameters.cc
+++ b/src/GenericParameters.cc
@@ -1,6 +1,5 @@
 #include "podio/GenericParameters.h"
 
-#include <algorithm>
 #include <iomanip>
 
 namespace podio {
diff --git a/src/RNTupleReader.cc b/src/RNTupleReader.cc
index 43c8370aa..d391e578a 100644
--- a/src/RNTupleReader.cc
+++ b/src/RNTupleReader.cc
@@ -1,5 +1,4 @@
 #include "podio/RNTupleReader.h"
-#include "podio/CollectionBase.h"
 #include "podio/CollectionBufferFactory.h"
 #include "podio/CollectionBuffers.h"
 #include "podio/CollectionIDTable.h"
diff --git a/src/RNTupleWriter.cc b/src/RNTupleWriter.cc
index b06f0d32e..caa18a5cb 100644
--- a/src/RNTupleWriter.cc
+++ b/src/RNTupleWriter.cc
@@ -1,7 +1,5 @@
 #include "podio/RNTupleWriter.h"
-#include "podio/CollectionBase.h"
 #include "podio/DatamodelRegistry.h"
-#include "podio/GenericParameters.h"
 #include "podio/SchemaEvolution.h"
 #include "podio/podioVersion.h"
 #include "rootUtils.h"
@@ -9,11 +7,8 @@
 #include "TFile.h"
 
 #include <ROOT/RField.hxx>
-#include <ROOT/RNTuple.hxx>
 #include <ROOT/RNTupleModel.hxx>
 
-#include <algorithm>
-
 namespace podio {
 
 RNTupleWriter::RNTupleWriter(const std::string& filename) :
diff --git a/src/ROOTLegacyReader.cc b/src/ROOTLegacyReader.cc
index 494ec4301..4a431dc42 100644
--- a/src/ROOTLegacyReader.cc
+++ b/src/ROOTLegacyReader.cc
@@ -14,9 +14,6 @@
 #include "TClass.h"
 #include "TFile.h"
 #include "TTree.h"
-#include "TTreeCache.h"
-
-#include <unordered_map>
 
 namespace podio {
 
diff --git a/src/ROOTReader.cc b/src/ROOTReader.cc
index 747235e86..1b4971601 100644
--- a/src/ROOTReader.cc
+++ b/src/ROOTReader.cc
@@ -11,7 +11,6 @@
 // ROOT specific includes
 #include "TChain.h"
 #include "TClass.h"
-#include "TTreeCache.h"
 
 #include <stdexcept>
 #include <unordered_map>
diff --git a/src/ROOTWriter.cc b/src/ROOTWriter.cc
index b43ac5f92..33f02741e 100644
--- a/src/ROOTWriter.cc
+++ b/src/ROOTWriter.cc
@@ -1,5 +1,4 @@
 #include "podio/ROOTWriter.h"
-#include "podio/CollectionBase.h"
 #include "podio/DatamodelRegistry.h"
 #include "podio/Frame.h"
 #include "podio/GenericParameters.h"
diff --git a/src/SIOLegacyReader.cc b/src/SIOLegacyReader.cc
index f1bd23af4..dcf3d9d18 100644
--- a/src/SIOLegacyReader.cc
+++ b/src/SIOLegacyReader.cc
@@ -1,5 +1,4 @@
 #include "podio/SIOLegacyReader.h"
-#include "podio/SIOBlock.h"
 
 #include "sioUtils.h"
 
diff --git a/src/SIOReader.cc b/src/SIOReader.cc
index de3d1e0e7..2609d611f 100644
--- a/src/SIOReader.cc
+++ b/src/SIOReader.cc
@@ -1,5 +1,4 @@
 #include "podio/SIOReader.h"
-#include "podio/SIOBlock.h"
 
 #include "sioUtils.h"
 
diff --git a/src/SIOWriter.cc b/src/SIOWriter.cc
index da5583e14..aef6e52e6 100644
--- a/src/SIOWriter.cc
+++ b/src/SIOWriter.cc
@@ -1,8 +1,5 @@
 #include "podio/SIOWriter.h"
-#include "podio/CollectionBase.h"
-#include "podio/CollectionIDTable.h"
 #include "podio/Frame.h"
-#include "podio/GenericParameters.h"
 #include "podio/SIOBlock.h"
 
 #include "sioUtils.h"
diff --git a/src/rootUtils.h b/src/rootUtils.h
index 131e0ef13..a473c6f0c 100644
--- a/src/rootUtils.h
+++ b/src/rootUtils.h
@@ -2,7 +2,6 @@
 #define PODIO_ROOT_UTILS_H // NOLINT(llvm-header-guard): internal headers confuse clang-tidy
 
 #include "podio/CollectionIDTable.h"
-#include "podio/GenericParameters.h"
 #include "podio/utilities/RootHelpers.h"
 
 #include "TBranch.h"
diff --git a/src/test_hashes.cpp b/src/test_hashes.cpp
index 41168ae58..bcceafa56 100644
--- a/src/test_hashes.cpp
+++ b/src/test_hashes.cpp
@@ -1,6 +1,5 @@
 #include "MurmurHash3.h"
 
-#include <algorithm>
 #include <fstream>
 #include <iomanip>
 #include <iostream>
diff --git a/tests/unittests/buffer_factory.cpp b/tests/unittests/buffer_factory.cpp
index 382451644..d97c09bd0 100644
--- a/tests/unittests/buffer_factory.cpp
+++ b/tests/unittests/buffer_factory.cpp
@@ -3,7 +3,6 @@
 
 #include "datamodel/DatamodelDefinition.h"
 #include "datamodel/ExampleClusterCollection.h"
-#include "datamodel/ExampleHitCollection.h"
 #include "datamodel/ExampleWithVectorMemberCollection.h"
 
 #include "catch2/catch_test_macros.hpp"
diff --git a/tests/unittests/interface_types.cpp b/tests/unittests/interface_types.cpp
index 400015843..a98b55b5d 100644
--- a/tests/unittests/interface_types.cpp
+++ b/tests/unittests/interface_types.cpp
@@ -2,10 +2,8 @@
 
 #include "podio/ObjectID.h"
 
-#include "datamodel/AnotherTypeWithEnergy.h"
-#include "datamodel/EnergyInNamespaceCollection.h"
-#include "datamodel/ExampleClusterCollection.h"
 #include "datamodel/ExampleHitCollection.h"
+#include "datamodel/MutableExampleCluster.h"
 #include "datamodel/TypeWithEnergy.h"
 
 #include <map>