diff --git a/.clang-tidy b/.clang-tidy
index b3cb96d..ad408a4 100644
--- a/.clang-tidy
+++ b/.clang-tidy
@@ -230,6 +230,7 @@
 readability-braces-around-statements,
 readability-const-return-type,
 readability-container-size-empty,
+readability-convert-member-functions-to-static,
 readability-delete-null-pointer,
 readability-deleted-default,
 readability-function-size,
diff --git a/src/item_updater.hpp b/src/item_updater.hpp
index 2bfd39c..bc8930e 100644
--- a/src/item_updater.hpp
+++ b/src/item_updater.hpp
@@ -181,7 +181,7 @@
     void syncToLatestImage();
 
     /** @brief Invoke the activation via DBus */
-    void invokeActivation(const std::unique_ptr<Activation>& activation);
+    static void invokeActivation(const std::unique_ptr<Activation>& activation);
 
     /** @brief Callback function for interfaces added signal.
      *
diff --git a/test/test_item_updater.cpp b/test/test_item_updater.cpp
index 096e15f..7fd1e7a 100644
--- a/test/test_item_updater.cpp
+++ b/test/test_item_updater.cpp
@@ -46,7 +46,7 @@
         return itemUpdater->activations;
     }
 
-    std::string getObjPath(const std::string& versionId)
+    static std::string getObjPath(const std::string& versionId)
     {
         return std::string(dBusPath) + "/" + versionId;
     }
diff --git a/test/test_version.cpp b/test/test_version.cpp
index d447e10..ee41bf1 100644
--- a/test/test_version.cpp
+++ b/test/test_version.cpp
@@ -45,7 +45,7 @@
         fs::remove_all(tmpDir);
     }
 
-    void writeFile(const fs::path& file, const char* data)
+    static void writeFile(const fs::path& file, const char* data)
     {
         std::ofstream f{file};
         f << data;