diff --git a/source/RobotAPI/libraries/armem/server/wm/detail/Prediction.h b/source/RobotAPI/libraries/armem/server/wm/detail/Prediction.h
index a438226d6f865764810a18cba5617f4d1288e696..3b2eccc022514313ceb0aaea7154e5c77258ea79 100644
--- a/source/RobotAPI/libraries/armem/server/wm/detail/Prediction.h
+++ b/source/RobotAPI/libraries/armem/server/wm/detail/Prediction.h
@@ -283,7 +283,7 @@ namespace armarx::armem::server::wm::detail
             // Get iterator to first entry of child ID (memory).
             std::vector<std::string> childItems = child.getItems();
 
-            size_t index = parentLength;
+            int index = parentLength;
             ARMARX_CHECK_FITS_SIZE(index, childItems.size());
 
             return childItems[index];
diff --git a/source/RobotAPI/libraries/armem_robot_state/common/localization/TransformHelper.h b/source/RobotAPI/libraries/armem_robot_state/common/localization/TransformHelper.h
index ae1e0bc5d1d6a355483cbd60626990f2065ffd9b..80cdea39921497a5c2c369416d59115d7dffc4c5 100644
--- a/source/RobotAPI/libraries/armem_robot_state/common/localization/TransformHelper.h
+++ b/source/RobotAPI/libraries/armem_robot_state/common/localization/TransformHelper.h
@@ -22,6 +22,7 @@
 #pragma once
 
 #include <vector>
+#include <optional>
 
 #include <Eigen/Core>
 #include <Eigen/Geometry>