diff --git a/src/libstore/binary-cache-store.hh b/src/libstore/binary-cache-store.hh
index bedb4c9f0..3f269b8cf 100644
--- a/src/libstore/binary-cache-store.hh
+++ b/src/libstore/binary-cache-store.hh
@@ -78,10 +78,10 @@ public:
     { return {}; }
 
     void querySubstitutablePathInfos(const PathSet & paths,
-        SubstitutablePathInfos & infos)
+        SubstitutablePathInfos & infos) override
     { }
 
-    bool wantMassQuery() { return wantMassQuery_; }
+    bool wantMassQuery() override { return wantMassQuery_; }
 
     void addToStore(const ValidPathInfo & info, const std::string & nar,
         bool repair = false, bool dontCheckSigs = false) override;
@@ -128,7 +128,7 @@ public:
 
     ref<FSAccessor> getFSAccessor() override;
 
-    void addSignatures(const Path & storePath, const StringSet & sigs)
+    void addSignatures(const Path & storePath, const StringSet & sigs) override
     { notImpl(); }
 
 };
diff --git a/src/libstore/s3-binary-cache-store.cc b/src/libstore/s3-binary-cache-store.cc
index 6ee27b48d..371bf24fd 100644
--- a/src/libstore/s3-binary-cache-store.cc
+++ b/src/libstore/s3-binary-cache-store.cc
@@ -56,7 +56,7 @@ struct S3BinaryCacheStoreImpl : public S3BinaryCacheStore
         diskCache = getNarInfoDiskCache();
     }
 
-    std::string getUri()
+    std::string getUri() override
     {
         return "s3://" + bucketName;
     }
@@ -69,7 +69,7 @@ struct S3BinaryCacheStoreImpl : public S3BinaryCacheStore
         return res;
     }
 
-    void init()
+    void init() override
     {
         if (!diskCache->cacheExists(getUri())) {
 
@@ -108,7 +108,7 @@ struct S3BinaryCacheStoreImpl : public S3BinaryCacheStore
        fetches the .narinfo file, rather than first checking for its
        existence via a HEAD request. Since .narinfos are small, doing
        a GET is unlikely to be slower than HEAD. */
-    bool isValidPathUncached(const Path & storePath)
+    bool isValidPathUncached(const Path & storePath) override
     {
         try {
             queryPathInfo(storePath);
@@ -118,7 +118,7 @@ struct S3BinaryCacheStoreImpl : public S3BinaryCacheStore
         }
     }
 
-    bool fileExists(const std::string & path)
+    bool fileExists(const std::string & path) override
     {
         stats.head++;
 
@@ -138,7 +138,7 @@ struct S3BinaryCacheStoreImpl : public S3BinaryCacheStore
         return true;
     }
 
-    void upsertFile(const std::string & path, const std::string & data)
+    void upsertFile(const std::string & path, const std::string & data) override
     {
         auto request =
             Aws::S3::Model::PutObjectRequest()
@@ -167,7 +167,7 @@ struct S3BinaryCacheStoreImpl : public S3BinaryCacheStore
         stats.putTimeMs += duration;
     }
 
-    std::shared_ptr<std::string> getFile(const std::string & path)
+    std::shared_ptr<std::string> getFile(const std::string & path) override
     {
         debug(format("fetching ‘s3://%1%/%2%’...") % bucketName % path);
 
diff --git a/src/nix/command.hh b/src/nix/command.hh
index 34affc43d..a29cdcf7f 100644
--- a/src/nix/command.hh
+++ b/src/nix/command.hh
@@ -49,6 +49,8 @@ public:
 
     StorePathsCommand();
 
+    using StoreCommand::run;
+
     virtual void run(ref<Store> store, Paths storePaths) = 0;
 
     void run(ref<Store> store) override;
diff --git a/src/nix/progress-bar.cc b/src/nix/progress-bar.cc
index 659d6572a..69811b282 100644
--- a/src/nix/progress-bar.cc
+++ b/src/nix/progress-bar.cc
@@ -89,7 +89,7 @@ public:
         state->progress[label].expected += value;
     }
 
-    void incProgress(const std::string & label, uint64_t value)
+    void incProgress(const std::string & label, uint64_t value) override
     {
         auto state(state_.lock());
         state->progress[label].progress += value;