diff --git a/drivers/staging/comedi/drivers/comedi_fc.c b/drivers/staging/comedi/drivers/comedi_fc.c
index ed0e79f5bfaa..6f872207ec3a 100644
--- a/drivers/staging/comedi/drivers/comedi_fc.c
+++ b/drivers/staging/comedi/drivers/comedi_fc.c
@@ -24,7 +24,7 @@
 
 /* Writes an array of data points to comedi's buffer */
 unsigned int cfc_write_array_to_buffer(struct comedi_subdevice *s,
-				       void *data, unsigned int num_bytes)
+				       const void *data, unsigned int num_bytes)
 {
 	struct comedi_async *async = s->async;
 	unsigned int retval;
diff --git a/drivers/staging/comedi/drivers/comedi_fc.h b/drivers/staging/comedi/drivers/comedi_fc.h
index c570c6eb6b9b..fa3de9e87325 100644
--- a/drivers/staging/comedi/drivers/comedi_fc.h
+++ b/drivers/staging/comedi/drivers/comedi_fc.h
@@ -35,8 +35,9 @@ static inline void cfc_inc_scan_progress(struct comedi_subdevice *s,
 }
 
 /* Writes an array of data points to comedi's buffer */
-unsigned int cfc_write_array_to_buffer(struct comedi_subdevice *,
-				       void *data, unsigned int num_bytes);
+unsigned int cfc_write_array_to_buffer(struct comedi_subdevice *s,
+				       const void *data,
+				       unsigned int num_bytes);
 
 static inline unsigned int cfc_write_to_buffer(struct comedi_subdevice *s,
 					       unsigned short data)