diff --git a/src/apps/rfc5769/rfc5769check.c b/src/apps/rfc5769/rfc5769check.c
index 70a17f1..0d19442 100644
--- a/src/apps/rfc5769/rfc5769check.c
+++ b/src/apps/rfc5769/rfc5769check.c
@@ -74,7 +74,7 @@ static int check_oauth(void) {
 
   size_t ltp_output_length = 0;
 
-  const char *base64encoded_ltp =
+  char *base64encoded_ltp =
       base64_encode((const unsigned char *)long_term_key, strlen(long_term_key), &ltp_output_length);
 
   const char mac_key[33] = "ZksjpweoixXmvn67534m";