diff --git a/lix/libcmd/repl-interacter.hh b/lix/libcmd/repl-interacter.hh
index 970368ec0..d3d7578d0 100644
--- a/lix/libcmd/repl-interacter.hh
+++ b/lix/libcmd/repl-interacter.hh
@@ -32,7 +32,7 @@ public:
     virtual ~ReplInteracter(){};
 };
 
-class ReadlineLikeInteracter : public virtual ReplInteracter
+class ReadlineLikeInteracter final : public ReplInteracter
 {
     std::string historyFile;
 public:
@@ -50,7 +50,7 @@ public:
     virtual ~ReadlineLikeInteracter() override;
 };
 
-class AutomationInteracter : public virtual ReplInteracter
+class AutomationInteracter final : public ReplInteracter
 {
 public:
     AutomationInteracter() = default;
diff --git a/lix/libstore/build/local-derivation-goal.cc b/lix/libstore/build/local-derivation-goal.cc
index d9d08082e..89ebc816d 100644
--- a/lix/libstore/build/local-derivation-goal.cc
+++ b/lix/libstore/build/local-derivation-goal.cc
@@ -966,7 +966,7 @@ bool LocalDerivationGoal::isAllowed(const DerivedPath & req)
 }
 
 
-struct RestrictedStoreConfig : virtual LocalFSStoreConfig
+struct RestrictedStoreConfig final : LocalFSStoreConfig
 {
     using LocalFSStoreConfig::LocalFSStoreConfig;
     const std::string name() override { return "Restricted Store"; }
diff --git a/lix/libstore/dummy-store.cc b/lix/libstore/dummy-store.cc
index 97fb484c4..caf333d80 100644
--- a/lix/libstore/dummy-store.cc
+++ b/lix/libstore/dummy-store.cc
@@ -3,7 +3,7 @@
 
 namespace nix {
 
-struct DummyStoreConfig : virtual StoreConfig {
+struct DummyStoreConfig final : StoreConfig {
     using StoreConfig::StoreConfig;
 
     const std::string name() override { return "Dummy Store"; }
@@ -16,7 +16,7 @@ struct DummyStoreConfig : virtual StoreConfig {
     }
 };
 
-struct DummyStore : public virtual Store
+struct DummyStore final : public Store
 {
     DummyStoreConfig config_;
 
diff --git a/lix/libstore/http-binary-cache-store.cc b/lix/libstore/http-binary-cache-store.cc
index c4f1922e7..3ed5dac01 100644
--- a/lix/libstore/http-binary-cache-store.cc
+++ b/lix/libstore/http-binary-cache-store.cc
@@ -8,7 +8,7 @@ namespace nix {
 
 MakeError(UploadToHTTP, Error);
 
-struct HttpBinaryCacheStoreConfig : virtual BinaryCacheStoreConfig
+struct HttpBinaryCacheStoreConfig final : BinaryCacheStoreConfig
 {
     using BinaryCacheStoreConfig::BinaryCacheStoreConfig;
 
@@ -22,7 +22,7 @@ struct HttpBinaryCacheStoreConfig : virtual BinaryCacheStoreConfig
     }
 };
 
-class HttpBinaryCacheStore : public virtual BinaryCacheStore
+class HttpBinaryCacheStore final : public BinaryCacheStore
 {
 private:
 
diff --git a/lix/libstore/legacy-ssh-store.cc b/lix/libstore/legacy-ssh-store.cc
index e9fbf543d..3c36fefe6 100644
--- a/lix/libstore/legacy-ssh-store.cc
+++ b/lix/libstore/legacy-ssh-store.cc
@@ -44,7 +44,7 @@ struct LegacySSHStoreConfigWithLog : LegacySSHStoreConfig
     const Setting<int> logFD{this, -1, "log-fd", "file descriptor to which SSH's stderr is connected"};
 };
 
-struct LegacySSHStore : public virtual Store
+struct LegacySSHStore final : public Store
 {
     LegacySSHStoreConfigWithLog config_;
 
diff --git a/lix/libstore/local-binary-cache-store.cc b/lix/libstore/local-binary-cache-store.cc
index 9772289bf..008f56ef6 100644
--- a/lix/libstore/local-binary-cache-store.cc
+++ b/lix/libstore/local-binary-cache-store.cc
@@ -7,7 +7,7 @@
 
 namespace nix {
 
-struct LocalBinaryCacheStoreConfig : virtual BinaryCacheStoreConfig
+struct LocalBinaryCacheStoreConfig final : BinaryCacheStoreConfig
 {
     using BinaryCacheStoreConfig::BinaryCacheStoreConfig;
 
@@ -21,7 +21,7 @@ struct LocalBinaryCacheStoreConfig : virtual BinaryCacheStoreConfig
     }
 };
 
-class LocalBinaryCacheStore : public virtual BinaryCacheStore
+class LocalBinaryCacheStore final : public BinaryCacheStore
 {
 private:
 
diff --git a/lix/libstore/local-store.hh b/lix/libstore/local-store.hh
index 81ae6f573..7ea86e1e0 100644
--- a/lix/libstore/local-store.hh
+++ b/lix/libstore/local-store.hh
@@ -37,7 +37,7 @@ struct OptimiseStats
     uint64_t blocksFreed = 0;
 };
 
-struct LocalStoreConfig : virtual LocalFSStoreConfig
+struct LocalStoreConfig final : LocalFSStoreConfig
 {
     using LocalFSStoreConfig::LocalFSStoreConfig;
 
diff --git a/lix/libstore/s3-binary-cache-store.cc b/lix/libstore/s3-binary-cache-store.cc
index 2cf6bac27..eb2927d44 100644
--- a/lix/libstore/s3-binary-cache-store.cc
+++ b/lix/libstore/s3-binary-cache-store.cc
@@ -184,7 +184,7 @@ S3Helper::FileTransferResult S3Helper::getObject(
     return res;
 }
 
-struct S3BinaryCacheStoreConfig : virtual BinaryCacheStoreConfig
+struct S3BinaryCacheStoreConfig final : BinaryCacheStoreConfig
 {
     using BinaryCacheStoreConfig::BinaryCacheStoreConfig;
 
diff --git a/lix/libstore/ssh-store.cc b/lix/libstore/ssh-store.cc
index 65bb28ddb..2c76cb707 100644
--- a/lix/libstore/ssh-store.cc
+++ b/lix/libstore/ssh-store.cc
@@ -27,7 +27,7 @@ struct SSHStoreConfig : virtual RemoteStoreConfig, virtual CommonSSHStoreConfig
     }
 };
 
-class SSHStore : public virtual RemoteStore
+class SSHStore final : public RemoteStore
 {
     SSHStoreConfig config_;
 
diff --git a/lix/nix/config.cc b/lix/nix/config.cc
index 5f744e9ec..6448af184 100644
--- a/lix/nix/config.cc
+++ b/lix/nix/config.cc
@@ -7,7 +7,7 @@
 
 using namespace nix;
 
-struct CmdConfig : virtual MultiCommand
+struct CmdConfig final : MultiCommand
 {
     CmdConfig() : MultiCommand(RegisterCommand::getCommandsFor({"config"}))
     { }
diff --git a/lix/nix/derivation.cc b/lix/nix/derivation.cc
index 8df5e64c6..5d0f4c2bb 100644
--- a/lix/nix/derivation.cc
+++ b/lix/nix/derivation.cc
@@ -2,7 +2,7 @@
 
 using namespace nix;
 
-struct CmdDerivation : virtual MultiCommand
+struct CmdDerivation final : MultiCommand
 {
     CmdDerivation() : MultiCommand(RegisterCommand::getCommandsFor({"derivation"}))
     { }
diff --git a/lix/nix/realisation.cc b/lix/nix/realisation.cc
index 80308e99f..4d02ca136 100644
--- a/lix/nix/realisation.cc
+++ b/lix/nix/realisation.cc
@@ -5,7 +5,7 @@
 
 using namespace nix;
 
-struct CmdRealisation : virtual MultiCommand
+struct CmdRealisation final : MultiCommand
 {
     CmdRealisation() : MultiCommand(RegisterCommand::getCommandsFor({"realisation"}))
     { }
diff --git a/lix/nix/registry.cc b/lix/nix/registry.cc
index 5bdba362b..80fd83760 100644
--- a/lix/nix/registry.cc
+++ b/lix/nix/registry.cc
@@ -204,7 +204,7 @@ struct CmdRegistryPin : RegistryCommand, EvalCommand
     }
 };
 
-struct CmdRegistry : virtual MultiCommand
+struct CmdRegistry final : MultiCommand
 {
     CmdRegistry()
         : MultiCommand({
diff --git a/lix/nix/store.cc b/lix/nix/store.cc
index 00f980088..599f544d1 100644
--- a/lix/nix/store.cc
+++ b/lix/nix/store.cc
@@ -2,7 +2,7 @@
 
 using namespace nix;
 
-struct CmdStore : virtual MultiCommand
+struct CmdStore final : MultiCommand
 {
     CmdStore() : MultiCommand(RegisterCommand::getCommandsFor({"store"}))
     { }