diff --git a/distrib/core/HOWTO b/distrib/core/HOWTO
index 470c97f4ea7a4c2251d12c312b5ae2a156b742c3..5c95b44b1ff2374b759475ac0ba54609981d68c1 100755
--- a/distrib/core/HOWTO
+++ b/distrib/core/HOWTO
@@ -1,3 +1,8 @@
+### first of all, check whether all tests pass
+cd /G/f2/pub
+mi
+ctest -j7
+
 cd /G/f2
 git checkout master
 git pull origin master
@@ -56,8 +61,8 @@ mkdir build
 cd build
 cmake ..
 m -j7
-ctest -j7
 mi
+ctest -j7
 
 ### upload man page (if changed)
 
diff --git a/pub/lib/obj.hpp b/pub/lib/obj.hpp
index b8698dd91d36f348cc173554872fe7b5ade090eb..616c831ce25353cb1c967021167fc2009a02acf3 100644
--- a/pub/lib/obj.hpp
+++ b/pub/lib/obj.hpp
@@ -47,8 +47,8 @@ class CObjNum : public CObj
 public:
     CObjNum() : CObj() {}
     bool is_vec() const { return false; }
-//    virtual double to_dr() const { return 0.; }
-//    virtual double to_dr(int i) const { return 0.; }
+    virtual double to_dr() const { return 0.; }
+    virtual double to_dr(int i) const { return 0.; }
     virtual RObjVecNum to_vec(int repetitions) const = 0;
 };