diff --git a/inst.c b/inst.c
index 7534717..a296ca3 100644
--- a/inst.c
+++ b/inst.c
@@ -1,8 +1,8 @@
 /*
  * inst.c - Instance structures
  *
- * Written 2009-2011 by Werner Almesberger
- * Copyright 2009-2011 by Werner Almesberger
+ * Written 2009-2012 by Werner Almesberger
+ * Copyright 2009-2012 by Werner Almesberger
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -1051,6 +1051,7 @@ int inst_meas(struct obj *obj, struct coord from, struct coord to)
 	assert(inst);
 	inst->base = from;
 	inst->u.meas.end = to;
+	inst->u.meas.valid = 1;
 	/* @@@ we still need to consider the text size as well */
 	update_bbox(&inst->bbox, from);
 	update_bbox(&inst->bbox, to);
@@ -1073,6 +1074,7 @@ void inst_meas_hint(struct obj *obj, unit_type offset)
 	inst = add_inst(&meas_ops, ip_meas, zero);
 	inst->obj = obj;
 	inst->u.meas.offset = offset;
+	inst->u.meas.valid = 0;
 	inst->active = 1; /* measurements are always active */
 }
 
diff --git a/inst.h b/inst.h
index daee9ae..badfb33 100644
--- a/inst.h
+++ b/inst.h
@@ -1,8 +1,8 @@
 /*
  * inst.h - Instance structures
  *
- * Written 2009, 2010 by Werner Almesberger
- * Copyright 2009, 2010 by Werner Almesberger
+ * Written 2009, 2010, 2012 by Werner Almesberger
+ * Copyright 2009, 2010, 2012 by Werner Almesberger
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -113,6 +113,7 @@ struct inst {
 		struct {
 			struct coord end;
 			double offset;
+			int valid;	/* only set if references exist */
 		} meas;
 	} u;
 	struct inst *next;
diff --git a/meas.c b/meas.c
index d551a2f..e505c68 100644
--- a/meas.c
+++ b/meas.c
@@ -1,8 +1,8 @@
 /*
  * meas.c - Measurements
  *
- * Written 2009, 2010 by Werner Almesberger
- * Copyright 2009, 2010 by Werner Almesberger
+ * Written 2009, 2010, 2012 by Werner Almesberger
+ * Copyright 2009, 2010, 2012 by Werner Almesberger
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -294,6 +294,22 @@ static int instantiate_meas_pkg(int n_frames)
 }
 
 
+static void purge_meas(struct pkg *pkg)
+{
+	struct inst **anchor, *inst;
+
+	anchor = pkg->insts+ip_meas;
+	while (*anchor)
+		if ((*anchor)->u.meas.valid) {
+			anchor = &(*anchor)->next;
+		} else {
+			inst = *anchor;
+			*anchor = inst->next;
+			free(inst);
+		}
+}
+
+
 int instantiate_meas(int n_frames)
 {
 	struct pkg *pkg;
@@ -304,6 +320,7 @@ int instantiate_meas(int n_frames)
 			inst_select_pkg(pkg->name);
 			if (!instantiate_meas_pkg(n_frames))
 				return 0;
+			purge_meas(pkg);
 		}
 	return 1;
 }