diff --git a/include/villas/nodes/comedi.h b/include/villas/nodes/comedi.h
index 3aa01f5b3..f7d938682 100644
--- a/include/villas/nodes/comedi.h
+++ b/include/villas/nodes/comedi.h
@@ -97,10 +97,10 @@ int comedi_start(struct node *n);
 int comedi_stop(struct node *n);
 
 /** @see node_type::read */
-int comedi_read(struct node *n, struct sample *smps[], unsigned cnt);
+int comedi_read(struct node *n, struct sample *smps[], unsigned cnt, unsigned *release);
 
 /** @see node_type::write */
-int comedi_write(struct node *n, struct sample *smps[], unsigned cnt);
+int comedi_write(struct node *n, struct sample *smps[], unsigned cnt, unsigned *release);
 
 /** @} */
 
diff --git a/include/villas/nodes/iec61850_sv.h b/include/villas/nodes/iec61850_sv.h
index 7213c20fb..347d448cb 100644
--- a/include/villas/nodes/iec61850_sv.h
+++ b/include/villas/nodes/iec61850_sv.h
@@ -95,9 +95,9 @@ int iec61850_sv_stop(struct node *n);
 
 int iec61850_sv_destroy(struct node *n);
 
-int iec61850_sv_read(struct node *n, struct sample *smps[], unsigned cnt);
+int iec61850_sv_read(struct node *n, struct sample *smps[], unsigned cnt, unsigned *released);
 
-int iec61850_sv_write(struct node *n, struct sample *smps[], unsigned cnt);
+int iec61850_sv_write(struct node *n, struct sample *smps[], unsigned cnt, unsigned *released);
 
 int iec61850_sv_fd(struct node *n);
 
diff --git a/lib/nodes/comedi.c b/lib/nodes/comedi.c
index 624cec3d8..2049d9ba3 100644
--- a/lib/nodes/comedi.c
+++ b/lib/nodes/comedi.c
@@ -525,7 +525,7 @@ int comedi_stop(struct node *n)
 
 #if COMEDI_USE_READ
 
-int comedi_read(struct node *n, struct sample *smps[], unsigned cnt)
+int comedi_read(struct node *n, struct sample *smps[], unsigned cnt, unsigned *release)
 {
 	int ret;
 	struct comedi *c = (struct comedi *) n->_vd;
@@ -648,7 +648,7 @@ int comedi_read(struct node *n, struct sample *smps[], unsigned cnt)
 
 #else
 
-int comedi_read(struct node *n, struct sample *smps[], unsigned cnt)
+int comedi_read(struct node *n, struct sample *smps[], unsigned cnt, unsigned *release)
 {
 	int ret;
 	struct comedi *c = (struct comedi *) n->_vd;
@@ -833,7 +833,7 @@ int comedi_read(struct node *n, struct sample *smps[], unsigned cnt)
 
 #endif
 
-int comedi_write(struct node *n, struct sample *smps[], unsigned cnt)
+int comedi_write(struct node *n, struct sample *smps[], unsigned cnt, unsigned *release)
 {
 	int ret;
 	struct comedi *c = (struct comedi *) n->_vd;
diff --git a/lib/nodes/iec61850_sv.c b/lib/nodes/iec61850_sv.c
index c4050dfb8..8945a61ae 100644
--- a/lib/nodes/iec61850_sv.c
+++ b/lib/nodes/iec61850_sv.c
@@ -344,7 +344,7 @@ int iec61850_sv_destroy(struct node *n)
 	return 0;
 }
 
-int iec61850_sv_read(struct node *n, struct sample *smps[], unsigned cnt)
+int iec61850_sv_read(struct node *n, struct sample *smps[], unsigned cnt, unsigned *released)
 {
 	int pulled;
 	struct iec61850_sv *i = (struct iec61850_sv *) n->_vd;
@@ -361,7 +361,7 @@ int iec61850_sv_read(struct node *n, struct sample *smps[], unsigned cnt)
 	return pulled;
 }
 
-int iec61850_sv_write(struct node *n, struct sample *smps[], unsigned cnt)
+int iec61850_sv_write(struct node *n, struct sample *smps[], unsigned cnt, unsigned *released)
 {
 	struct iec61850_sv *i = (struct iec61850_sv *) n->_vd;