diff --git a/src/openvpn/dns.c b/src/openvpn/dns.c
index c00d4b9c..38739923 100644
--- a/src/openvpn/dns.c
+++ b/src/openvpn/dns.c
@@ -45,7 +45,7 @@
  * @return              True if parsing was successful
  */
 static bool
-dns_server_port_parse(in_port_t *port, char *port_str)
+dns_server_port_parse(in_port_t *port, const char *port_str)
 {
     char *endptr;
     errno = 0;
@@ -71,8 +71,8 @@ dns_server_addr_parse(struct dns_server *server, const char *addr)
     in_port_t port = 0;
     sa_family_t af;

-    char *first_colon = strchr(addr, ':');
-    char *last_colon = strrchr(addr, ':');
+    const char *first_colon = strchr(addr, ':');
+    const char *last_colon = strrchr(addr, ':');

     if (!first_colon || first_colon == last_colon)
     {
@@ -93,7 +93,7 @@ dns_server_addr_parse(struct dns_server *server, const char *addr)
         if (addr[0] == '[')
         {
             addr += 1;
-            char *bracket = last_colon - 1;
+            const char *bracket = last_colon - 1;
             if (*bracket != ']' || bracket == addr || !dns_server_port_parse(&port, last_colon + 1))
             {
                 return false;
---
 src/openvpn/ntlm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/openvpn/ntlm.c b/src/openvpn/ntlm.c
index 8e913dce..244ee945 100644
--- a/src/openvpn/ntlm.c
+++ b/src/openvpn/ntlm.c
@@ -218,7 +218,7 @@ ntlm_phase_3(const struct http_proxy_info *p, const char *phase_2, struct gc_are
 
     char domain[128];
     char username[128];
-    char *separator;
+    const char *separator;
 
     ASSERT(strlen(p->up.username) > 0);
     ASSERT(strlen(p->up.password) > 0);