diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index a58dd1535..0c25be95c 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -104,7 +104,7 @@ struct StoreConfig : public Config
 
     StoreConfig() = delete;
 
-    StringSet getDefaultSystemFeatures();
+    static StringSet getDefaultSystemFeatures();
 
     virtual ~StoreConfig() { }