diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index d3d7a315e..f4a3ab0e3 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -105,7 +105,7 @@ struct StoreConfig : public Config
 
     StoreConfig() = delete;
 
-    StringSet getDefaultSystemFeatures();
+    static StringSet getDefaultSystemFeatures();
 
     virtual ~StoreConfig() { }