diff --git a/lily/include/lily-guile-macros.hh b/lily/include/lily-guile-macros.hh
index 7002c0f..dcb0a13 100644
--- a/lily/include/lily-guile-macros.hh
+++ b/lily/include/lily-guile-macros.hh
@@ -29,6 +29,14 @@ #endif
 
 #ifdef CACHE_SYMBOLS
 
+/* this lets us "overload" macros such as get_property to take
+   symbols as well as strings */
+inline SCM
+scm_or_str2symbol (char const *c) { return scm_str2symbol (c); }
+
+inline SCM
+scm_or_str2symbol (SCM s) { return s; }
+
 /* Using this trick we cache the value of scm_str2symbol ("fooo") where
    "fooo" is a constant string. This is done at the cost of one static
    variable per ly_symbol2scm() use, and one boolean evaluation for
@@ -43,10 +51,10 @@ #define ly_symbol2scm(x)						\
     if (__builtin_constant_p ((x)))					\
       {									\
 	if (!cached)							\
-	  value = cached = scm_gc_protect_object (scm_str2symbol ((x))); \
+	  value = cached = scm_gc_protect_object (scm_or_str2symbol (x)); \
       }									\
     else								\
-      value = scm_str2symbol ((char *) (x));				\
+      value = scm_or_str2symbol (x);					\
     value;								\
   })
 #else
diff --git a/lily/tweak-engraver.cc b/lily/tweak-engraver.cc
index a479935..1749228 100644
--- a/lily/tweak-engraver.cc
+++ b/lily/tweak-engraver.cc
@@ -33,7 +33,7 @@ Tweak_engraver::acknowledge_grob (Grob_i
       for (SCM s = music->get_property ("tweaks");
 	   scm_is_pair (s); s = scm_cdr (s))
 	{
-	  info.grob ()->internal_set_property (scm_caar (s), scm_cdar (s), __FILE__, __LINE__);
+	  info.grob ()->set_property (scm_caar (s), scm_cdar (s));
 	}
     }
 }