diff --git a/src/openvpn/proxy.c b/src/openvpn/proxy.c
index c9043014cda..5c1cdcb6d11 100644
--- a/src/openvpn/proxy.c
+++ b/src/openvpn/proxy.c
@@ -948,17 +948,21 @@ establish_http_proxy_passthru(struct http_proxy_info *p,
                 }
 
                 /* send digest response */
-                openvpn_snprintf(buf, sizeof(buf), "Proxy-Authorization: Digest username=\"%s\", realm=\"%s\", nonce=\"%s\", uri=\"%s\", qop=%s, nc=%s, cnonce=\"%s\", response=\"%s\"%s",
-                                 username,
-                                 realm,
-                                 nonce,
-                                 uri,
-                                 qop,
-                                 nonce_count,
-                                 cnonce,
-                                 response,
-                                 opaque_kv
-                                 );
+                int sret = openvpn_snprintf(buf, sizeof(buf), "Proxy-Authorization: Digest username=\"%s\", realm=\"%s\", nonce=\"%s\", uri=\"%s\", qop=%s, nc=%s, cnonce=\"%s\", response=\"%s\"%s",
+                                            username,
+                                            realm,
+                                            nonce,
+                                            uri,
+                                            qop,
+                                            nonce_count,
+                                            cnonce,
+                                            response,
+                                            opaque_kv
+                                            );
+                if (sret >= sizeof(buf))
+                {
+                    goto error;
+                }
                 msg(D_PROXY, "Send to HTTP proxy: '%s'", buf);
                 if (!send_line_crlf(sd, buf))
                 {
diff --git a/src/openvpn/socks.c b/src/openvpn/socks.c
index d842666ebee..b0469102552 100644
--- a/src/openvpn/socks.c
+++ b/src/openvpn/socks.c
@@ -109,8 +109,11 @@ socks_username_password_auth(struct socks_proxy_info *p,
             "Authentication not possible.");
         goto cleanup;
     }
-    openvpn_snprintf(to_send, sizeof(to_send), "\x01%c%s%c%s", (int) strlen(creds.username),
-                     creds.username, (int) strlen(creds.password), creds.password);
+    int sret = openvpn_snprintf(to_send, sizeof(to_send), "\x01%c%s%c%s",
+                                (int) strlen(creds.username), creds.username,
+                                (int) strlen(creds.password), creds.password);
+    ASSERT(sret <= sizeof(to_send));
+
     size = send(sd, to_send, strlen(to_send), MSG_NOSIGNAL);
 
     if (size != strlen(to_send))
diff --git a/src/openvpn/ssl_openssl.c b/src/openvpn/ssl_openssl.c
index 4383e98193b..6f29c3d7d1d 100644
--- a/src/openvpn/ssl_openssl.c
+++ b/src/openvpn/ssl_openssl.c
@@ -2069,7 +2069,7 @@ print_pkey_details(EVP_PKEY *pkey, char *buf, size_t buflen)
 #endif
 
 #ifndef OPENSSL_NO_EC
-    char groupname[256];
+    char groupname[64];
     if (is_ec)
     {
         size_t len;
@@ -2130,7 +2130,7 @@ static void
 print_cert_details(X509 *cert, char *buf, size_t buflen)
 {
     EVP_PKEY *pkey = X509_get_pubkey(cert);
-    char pkeybuf[128] = { 0 };
+    char pkeybuf[64] = { 0 };
     print_pkey_details(pkey, pkeybuf, sizeof(pkeybuf));
 
     char sig[128] = { 0 };
diff --git a/src/openvpn/tls_crypt.c b/src/openvpn/tls_crypt.c
index 975d31fafb5..6ef1c7d618c 100644
--- a/src/openvpn/tls_crypt.c
+++ b/src/openvpn/tls_crypt.c
@@ -575,7 +575,7 @@ tls_crypt_v2_verify_metadata(const struct tls_wrap_ctx *ctx,
 
     char metadata_type_str[4] = { 0 }; /* Max value: 255 */
     openvpn_snprintf(metadata_type_str, sizeof(metadata_type_str),
-                     "%i", metadata_type);
+                     "%i", (uint8_t) metadata_type);
     struct env_set *es = env_set_create(NULL);
     setenv_str(es, "script_type", "tls-crypt-v2-verify");
     setenv_str(es, "metadata_type", metadata_type_str);
diff --git a/src/openvpnserv/interactive.c b/src/openvpnserv/interactive.c
index 452633c6e3c..d32223cea5b 100644
--- a/src/openvpnserv/interactive.c
+++ b/src/openvpnserv/interactive.c
@@ -33,6 +33,7 @@
 #include <sddl.h>
 #include <shellapi.h>
 #include <mstcpip.h>
+#include <inttypes.h>
 
 #include <versionhelpers.h>
 
@@ -2002,7 +2003,7 @@ RunOpenvpn(LPVOID p)
         ReturnLastError(pipe, L"malloc");
         goto out;
     }
-    openvpn_swprintf(cmdline, cmdline_size, L"openvpn %ls --msg-channel %lu",
+    openvpn_swprintf(cmdline, cmdline_size, L"openvpn %ls --msg-channel %" PRIuPTR,
                      sud.options, svc_pipe);
 
     if (!CreateEnvironmentBlock(&user_env, imp_token, FALSE))