diff --git a/src/fdb5/database/Key.cc b/src/fdb5/database/Key.cc
index d88a74986..d3f73ed81 100644
--- a/src/fdb5/database/Key.cc
+++ b/src/fdb5/database/Key.cc
@@ -134,14 +134,6 @@ void BaseKey::popFrom(const BaseKey& other) {
     for (const auto& [keyword, value] : other) { pop(keyword); }
 }
 
-void Key::pushFrom(const Key& other) {
-    for (const auto& [keyword, value] : Reverse(other)) { push(keyword, value); }
-}
-
-void Key::popFrom(const Key& other) {
-    for (const auto& [keyword, value] : other) { pop(keyword); }
-}
-
 const std::string &BaseKey::get( const std::string &k ) const {
     eckit::StringDict::const_iterator i = keys_.find(k);
     if ( i == keys_.end() ) {
diff --git a/src/fdb5/database/Key.h b/src/fdb5/database/Key.h
index 9a7c1f9ca..2d5b436c9 100644
--- a/src/fdb5/database/Key.h
+++ b/src/fdb5/database/Key.h
@@ -68,8 +68,9 @@ class BaseKey {
 
     void push(const std::string &k, const std::string &v);
     void pop(const std::string &k);
-    void pushFrom(const Key& other);
-    void popFrom(const Key& other);
+
+    void pushFrom(const BaseKey& other);
+    void popFrom(const BaseKey& other);
 
     const std::string& get( const std::string &k ) const;
 
diff --git a/src/fdb5/rules/Matcher.cc b/src/fdb5/rules/Matcher.cc
index ab332d3b9..7590e22ad 100644
--- a/src/fdb5/rules/Matcher.cc
+++ b/src/fdb5/rules/Matcher.cc
@@ -19,12 +19,6 @@ namespace fdb5 {
 
 //----------------------------------------------------------------------------------------------------------------------
 
-Matcher::Matcher() {
-}
-
-Matcher::~Matcher() {
-}
-
 bool Matcher::optional() const {
     return false;
 }
diff --git a/src/fdb5/rules/Matcher.h b/src/fdb5/rules/Matcher.h
index 57b1b2f27..c61cc6c6c 100644
--- a/src/fdb5/rules/Matcher.h
+++ b/src/fdb5/rules/Matcher.h
@@ -31,7 +31,6 @@ namespace fdb5 {
 
 class Key;
 class TypedKey;
-class Key;
 class TypesRegistry;
 
 //----------------------------------------------------------------------------------------------------------------------
diff --git a/src/fdb5/rules/Schema.cc b/src/fdb5/rules/Schema.cc
index d4cdbf133..c22827d47 100644
--- a/src/fdb5/rules/Schema.cc
+++ b/src/fdb5/rules/Schema.cc
@@ -53,21 +53,21 @@ Schema::~Schema() {
 
 //----------------------------------------------------------------------------------------------------------------------
 
-const Rule* Schema::matchingRule(const Key& dbKey, const Key& idxKey) const {
+const RuleDatum& Schema::matchingRule(const Key& dbKey, const Key& idxKey) const {
 
     for (const auto& dbRule : rules_) {
         if (!dbRule.match(dbKey)) { continue; }
         for (const auto& idxRule : dbRule.rules()) {
             if (idxRule.match(idxKey)) {
                 /// @note this assumes that there is only one datum per index
-                for (const auto& datumRule : idxRule.rules()) { return &datumRule; }
+                for (const auto& datumRule : idxRule.rules()) { return datumRule; }
             }
         }
     }
 
-    LOG_DEBUG_LIB(LibFdb5) << "No rule is matching dbKey=" << dbKey << " and idxKey=" << idxKey << std::endl;
-
-    return nullptr;
+    std::ostringstream msg;
+    msg << "No rule is matching dbKey=" << dbKey << " and idxKey=" << idxKey << std::endl;
+    throw eckit::SeriousBug(msg.str(), Here());
 }
 
 const RuleDatabase& Schema::matchingRule(const Key& dbKey) const {
@@ -76,7 +76,7 @@ const RuleDatabase& Schema::matchingRule(const Key& dbKey) const {
         if (rule.match(dbKey)) { return rule; }
     }
 
-    std::stringstream msg;
+    std::ostringstream msg;
     msg << "No rule exists for key " << dbKey;
     throw eckit::SeriousBug(msg.str(), Here());
 }
diff --git a/src/fdb5/rules/Schema.h b/src/fdb5/rules/Schema.h
index 8fccf5b3d..5e09346b0 100644
--- a/src/fdb5/rules/Schema.h
+++ b/src/fdb5/rules/Schema.h
@@ -70,8 +70,7 @@ class Schema : private eckit::NonCopyable {
 
     const RuleDatabase& matchingRule(const Key& dbKey) const;
 
-    /// @todo return RuleDatum
-    const Rule* matchingRule(const Key& dbKey, const Key& idxKey) const;
+    const RuleDatum& matchingRule(const Key& dbKey, const Key& idxKey) const;
 
     void load(const eckit::PathName& path, bool replace = false);
 
diff --git a/src/fdb5/tools/fdb-overlay.cc b/src/fdb5/tools/fdb-overlay.cc
index 6584e9cc8..5adb126c4 100644
--- a/src/fdb5/tools/fdb-overlay.cc
+++ b/src/fdb5/tools/fdb-overlay.cc
@@ -117,7 +117,7 @@ void FdbOverlay::execute(const CmdArgs& args) {
         }
     }
 
-    std::unique_ptr<DB> dbSource = DB::buildReader(source.canonical(), conf);
+    std::unique_ptr<DB> dbSource = DB::buildReader(source, conf);
     if (!dbSource->exists()) {
         std::stringstream ss;
         ss << "Source database not found: " << source << std::endl;
@@ -130,7 +130,7 @@ void FdbOverlay::execute(const CmdArgs& args) {
         throw eckit::UserError(ss.str(), Here());
     }
 
-    std::unique_ptr<DB> dbTarget = DB::buildReader(target.canonical(), conf);
+    std::unique_ptr<DB> dbTarget = DB::buildReader(target, conf);
 
     if (remove_) {
         if (!dbTarget->exists()) {
diff --git a/src/fdb5/types/TypesRegistry.h b/src/fdb5/types/TypesRegistry.h
index 9745a4f4e..e127b8bdb 100644
--- a/src/fdb5/types/TypesRegistry.h
+++ b/src/fdb5/types/TypesRegistry.h
@@ -16,13 +16,10 @@
 #ifndef fdb5_TypesRegistry_H
 #define fdb5_TypesRegistry_H
 
-#include <string>
+#include <functional>
 #include <map>
-#include <memory>
 #include <optional>
-#include <functional>
-
-#include "eckit/memory/NonCopyable.h"
+#include <string>
 
 namespace fdb5 {
 
@@ -30,12 +27,18 @@ class Type;
 
 //----------------------------------------------------------------------------------------------------------------------
 
-class TypesRegistry : private eckit::NonCopyable {
+class TypesRegistry {
 
 public: // methods
 
     TypesRegistry();
 
+    TypesRegistry(const TypesRegistry&)            = delete;
+    TypesRegistry& operator=(const TypesRegistry&) = delete;
+
+    TypesRegistry(TypesRegistry&&)            = default;
+    TypesRegistry& operator=(TypesRegistry&&) = default;
+
     ~TypesRegistry();
 
     const Type &lookupType(const std::string &keyword) const;
@@ -45,7 +48,6 @@ class TypesRegistry : private eckit::NonCopyable {
     void dump( std::ostream &out ) const;
     void dump( std::ostream &out, const std::string &keyword ) const;
 
-
 private: // members
 
     typedef std::map<std::string, Type *> TypeMap;
@@ -57,8 +59,7 @@ class TypesRegistry : private eckit::NonCopyable {
 
     friend std::ostream &operator<<(std::ostream &s, const TypesRegistry &x);
 
-    void print( std::ostream &out ) const;
-
+    void print(std::ostream& out) const;
 };
 
 //----------------------------------------------------------------------------------------------------------------------