diff --git a/demo/cmd.c b/demo/cmd.c
index 51b7e3c..20d8b2d 100644
--- a/demo/cmd.c
+++ b/demo/cmd.c
@@ -34,7 +34,6 @@ static comedi_range * range_info[N_CHANS];
 static lsampl_t maxdata[N_CHANS];
 
 
-int prepare_cmd_lib(comedi_t *dev, int subdevice, int n_scan, int n_chan, unsigned period_nanosec, comedi_cmd *cmd);
 int prepare_cmd_lib(comedi_t *dev, int subdevice, int n_scan, int n_chan, unsigned period_nanosec, comedi_cmd *cmd);
 
 void do_cmd(comedi_t *dev,comedi_cmd *cmd);