diff --git a/src/openvpn/ssl_mbedtls.c b/src/openvpn/ssl_mbedtls.c
index a62ff76..85c771a 100644
--- a/src/openvpn/ssl_mbedtls.c
+++ b/src/openvpn/ssl_mbedtls.c
@@ -1572,7 +1572,7 @@
 {
     static char mbedtls_version[30];
     unsigned int pv = mbedtls_version_get_number();
-    snprintf(mbedtls_version, sizeof(mbedtls_version), "mbed TLS %d.%d.%d", (pv >> 24) & 0xff,
+    snprintf(mbedtls_version, sizeof(mbedtls_version), "mbed TLS %u.%u.%u", (pv >> 24) & 0xff,
              (pv >> 16) & 0xff, (pv >> 8) & 0xff);
     return mbedtls_version;
 }