diff --git a/programs/ssl/ssl_mail_client.c b/programs/ssl/ssl_mail_client.c
index f26a23ba4f..ccd9dc9345 100644
--- a/programs/ssl/ssl_mail_client.c
+++ b/programs/ssl/ssl_mail_client.c
@@ -727,7 +727,7 @@ usage:
     mbedtls_printf("  > Write MAIL FROM to server:");
     fflush(stdout);
 
-    len = snprintf((char *) buf, sizeof(buf), "MAIL FROM:<%s>\r\n", opt.mail_from);
+    len = mbedtls_snprintf((char *) buf, sizeof(buf), "MAIL FROM:<%s>\r\n", opt.mail_from);
     ret = write_ssl_and_get_response(&ssl, buf, len);
     if (ret < 200 || ret > 299) {
         mbedtls_printf(" failed\n  ! server responded with %d\n\n", ret);
@@ -739,7 +739,7 @@ usage:
     mbedtls_printf("  > Write RCPT TO to server:");
     fflush(stdout);
 
-    len = snprintf((char *) buf, sizeof(buf), "RCPT TO:<%s>\r\n", opt.mail_to);
+    len = mbedtls_snprintf((char *) buf, sizeof(buf), "RCPT TO:<%s>\r\n", opt.mail_to);
     ret = write_ssl_and_get_response(&ssl, buf, len);
     if (ret < 200 || ret > 299) {
         mbedtls_printf(" failed\n  ! server responded with %d\n\n", ret);
@@ -763,7 +763,7 @@ usage:
     mbedtls_printf("  > Write content to server:");
     fflush(stdout);
 
-    len = snprintf((char *) buf, sizeof(buf),
+    len = mbedtls_snprintf((char *) buf, sizeof(buf),
                    "From: %s\r\nSubject: Mbed TLS Test mail\r\n\r\n"
                    "This is a simple test mail from the "
                    "Mbed TLS mail client example.\r\n"