diff --git a/lib/ftp.c b/lib/ftp.c
index 4deb841b3a..8881bd364a 100644
--- a/lib/ftp.c
+++ b/lib/ftp.c
@@ -272,7 +272,7 @@ static CURLcode ftp_cw_lc_write(struct Curl_easy *data,
                                 struct Curl_cwriter *writer, int type,
                                 const char *buf, size_t blen)
 {
-  static char nl = '\n';
+  static const char nl = '\n';
   struct ftp_cw_lc_ctx *ctx = (struct ftp_cw_lc_ctx *)writer;
 
   if(!(type & CLIENTWRITE_BODY) ||