diff --git a/src/muz/rel/dl_vector_relation.h b/src/muz/rel/dl_vector_relation.h
index 114f4ca43..4d0917359 100644
--- a/src/muz/rel/dl_vector_relation.h
+++ b/src/muz/rel/dl_vector_relation.h
@@ -62,8 +62,6 @@ namespace datalog {
             dealloc(m_elems);
         }
 
-        virtual bool can_swap() const { return true; }
-
         virtual void swap(relation_base& other) {
             vector_relation& o = dynamic_cast<vector_relation&>(other);
             if (&o == this) return;
diff --git a/src/util/debug.h b/src/util/debug.h
index 9e519982f..a36743f73 100644
--- a/src/util/debug.h
+++ b/src/util/debug.h
@@ -73,7 +73,7 @@ bool is_debug_enabled(const char * tag);
         UNREACHABLE();                                          \
     }                                                           
 #else
-#define VERIFY(_x_) (_x_)
+#define VERIFY(_x_) (void)(_x_)
 #endif
 
 #define MAKE_NAME2(LINE) zofty_ ## LINE