diff --git a/tests/libtest/lib571.c b/tests/libtest/lib571.c
index a24a69bc40..2cf4128e7a 100644
--- a/tests/libtest/lib571.c
+++ b/tests/libtest/lib571.c
@@ -45,11 +45,10 @@
 
 static int rtp_packet_count = 0;
 
-static size_t rtp_write(char *ptr, size_t size, size_t nmemb, void *stream)
+static size_t rtp_write(char *data, size_t size, size_t nmemb, void *stream)
 {
   static const char *RTP_DATA = "$_1234\n\0Rsdf";
 
-  char *data = (char *)ptr;
   int channel = RTP_PKT_CHANNEL(data);
   int message_size;
   int coded_size = RTP_PKT_LENGTH(data);