diff --git a/lily/bar-line.cc b/lily/bar-line.cc
index 2a9cf9d..c8f377b 100644
--- a/lily/bar-line.cc
+++ b/lily/bar-line.cc
@@ -26,21 +26,21 @@
 #include "output-def.hh"
 #include "paper-column.hh"
 #include "staff-symbol-referencer.hh"
+#include "staff-symbol.hh"
 
 MAKE_SCHEME_CALLBACK (Bar_line, calc_bar_extent, 1)
 SCM
 Bar_line::calc_bar_extent (SCM smob)
 {
+  Interval result;
   Grob *me = unsmob_grob (smob);
+  if (Grob *staff = Staff_symbol_referencer::get_staff_symbol (me))
+    {
+      Real ss = Staff_symbol::staff_space (staff);
+      result = Staff_symbol::line_span (staff) * (ss / 2.0);
+    }
 
-  SCM size = me->get_property ("bar-size");
-
-  if (!scm_is_number (size)
-      || !Staff_symbol_referencer::get_staff_symbol (me))
-    return ly_interval2scm (Interval ());
-
-  Real h = scm_to_double (size);
-  return ly_interval2scm (Interval (-h / 2, h / 2));
+  return ly_interval2scm (result);
 }
 
 Interval