diff --git a/src/fdb5/daos/DaosArrayHandle.h b/src/fdb5/daos/DaosArrayHandle.h
index 69adb2b74..b7da5d37d 100644
--- a/src/fdb5/daos/DaosArrayHandle.h
+++ b/src/fdb5/daos/DaosArrayHandle.h
@@ -13,6 +13,7 @@
 
 #pragma once
 
+#include <optional>
 #include "eckit/io/DataHandle.h"
 
 #include "fdb5/daos/DaosSession.h"
diff --git a/src/fdb5/daos/DaosArrayPartHandle.h b/src/fdb5/daos/DaosArrayPartHandle.h
index 6799de2c4..e57233d6c 100644
--- a/src/fdb5/daos/DaosArrayPartHandle.h
+++ b/src/fdb5/daos/DaosArrayPartHandle.h
@@ -13,6 +13,8 @@
 
 #pragma once
 
+#include <optional>
+
 #include "eckit/io/DataHandle.h"
 
 #include "fdb5/daos/DaosSession.h"
diff --git a/src/fdb5/daos/DaosCatalogue.cc b/src/fdb5/daos/DaosCatalogue.cc
index 1256a6d5c..21fb0073d 100644
--- a/src/fdb5/daos/DaosCatalogue.cc
+++ b/src/fdb5/daos/DaosCatalogue.cc
@@ -8,6 +8,8 @@
  * does it submit to any jurisdiction.
  */
 
+#include <optional>
+
 #include "eckit/config/Resource.h"
 #include "eckit/serialisation/MemoryStream.h"
 
diff --git a/src/fdb5/daos/DaosKeyValueHandle.h b/src/fdb5/daos/DaosKeyValueHandle.h
index 3d6fab91a..d7afa44b8 100644
--- a/src/fdb5/daos/DaosKeyValueHandle.h
+++ b/src/fdb5/daos/DaosKeyValueHandle.h
@@ -13,6 +13,8 @@
 
 #pragma once
 
+#include <optional>
+
 #include "eckit/io/DataHandle.h"
 
 #include "fdb5/daos/DaosName.h"
diff --git a/src/fdb5/database/Index.h b/src/fdb5/database/Index.h
index 8b07f73d0..3705fbef5 100755
--- a/src/fdb5/database/Index.h
+++ b/src/fdb5/database/Index.h
@@ -16,6 +16,8 @@
 #define fdb5_Index_H
 
 #include <memory>
+#include <optional>
+#include <functional>
 
 #include "eckit/eckit.h"
 
diff --git a/src/fdb5/database/Key.h b/src/fdb5/database/Key.h
index 65299e2de..023c05c33 100644
--- a/src/fdb5/database/Key.h
+++ b/src/fdb5/database/Key.h
@@ -21,6 +21,7 @@
 #include <utility>
 #include <set>
 #include <memory>
+#include <functional>
 
 #include "eckit/types/Types.h"
 
diff --git a/src/fdb5/types/TypesRegistry.h b/src/fdb5/types/TypesRegistry.h
index 246565eba..9745a4f4e 100644
--- a/src/fdb5/types/TypesRegistry.h
+++ b/src/fdb5/types/TypesRegistry.h
@@ -19,6 +19,8 @@
 #include <string>
 #include <map>
 #include <memory>
+#include <optional>
+#include <functional>
 
 #include "eckit/memory/NonCopyable.h"