diff --git a/src/libexpr/lexer.l b/src/libexpr/lexer.l
index 225ab3287..7298419d9 100644
--- a/src/libexpr/lexer.l
+++ b/src/libexpr/lexer.l
@@ -12,7 +12,9 @@
 
 
 %{
+#ifdef __clang__
 #pragma clang diagnostic ignored "-Wunneeded-internal-declaration"
+#endif
 
 #include <boost/lexical_cast.hpp>
 
diff --git a/src/libutil/archive.hh b/src/libutil/archive.hh
index fe22435ef..9e9e11b1a 100644
--- a/src/libutil/archive.hh
+++ b/src/libutil/archive.hh
@@ -82,7 +82,7 @@ struct RetrieveRegularNARSink : ParseSink
         sink(data);
     }
 
-    void createSymlink(const Path & path, const string & target)
+    void createSymlink(const Path & path, const string & target) override
     {
         regular = false;
     }