diff --git a/lib/cf-socket.c b/lib/cf-socket.c
index b059a3cfe2..1511d6f036 100644
--- a/lib/cf-socket.c
+++ b/lib/cf-socket.c
@@ -86,14 +86,15 @@
 #endif
 
 /* retrieves ip address and port from a sockaddr structure. note it calls
- * curlx_inet_ntop which sets errno on fail, not SOCKERRNO.
+ * curlx_inet_ntop() and returns CURLcode.
  * @unittest 1607
  */
-UNITTEST bool sockaddr2string(struct sockaddr *sa, curl_socklen_t salen,
-                              char *addr, uint16_t *port);
-UNITTEST bool sockaddr2string(struct sockaddr *sa, curl_socklen_t salen,
-                              char *addr, uint16_t *port)
+UNITTEST CURLcode sockaddr2string(struct sockaddr *sa, curl_socklen_t salen,
+                                  char *addr, uint16_t *port);
+UNITTEST CURLcode sockaddr2string(struct sockaddr *sa, curl_socklen_t salen,
+                                  char *addr, uint16_t *port)
 {
+  CURLcode result;
   struct sockaddr_in *si = NULL;
 #ifdef USE_IPV6
   struct sockaddr_in6 *si6 = NULL;
@@ -107,17 +108,21 @@ UNITTEST bool sockaddr2string(struct sockaddr *sa, curl_socklen_t salen,
   switch(sa->sa_family) {
   case AF_INET:
     si = (struct sockaddr_in *)(void *)sa;
-    if(curlx_inet_ntop(sa->sa_family, &si->sin_addr, addr, MAX_IPADR_LEN)) {
+    result = curlx_inet_ntop(sa->sa_family, &si->sin_addr, addr,
+                             MAX_IPADR_LEN);
+    if(!result) {
       *port = ntohs(si->sin_port);
-      return TRUE;
+      return result;
     }
     break;
 #ifdef USE_IPV6
   case AF_INET6:
     si6 = (struct sockaddr_in6 *)(void *)sa;
-    if(curlx_inet_ntop(sa->sa_family, &si6->sin6_addr, addr, MAX_IPADR_LEN)) {
+    result = curlx_inet_ntop(sa->sa_family, &si6->sin6_addr, addr,
+                             MAX_IPADR_LEN);
+    if(!result) {
       *port = ntohs(si6->sin6_port);
-      return TRUE;
+      return result;
     }
     break;
 #endif
@@ -130,16 +135,16 @@ UNITTEST bool sockaddr2string(struct sockaddr *sa, curl_socklen_t salen,
     else
       addr[0] = 0; /* socket with no name */
     *port = 0;
-    return TRUE;
+    return CURLE_OK;
 #endif
   default:
+    result = CURLE_UNSUPPORTED_PROTOCOL;
     break;
   }
 
   addr[0] = '\0';
   *port = 0;
-  errno = SOCKEAFNOSUPPORT;
-  return FALSE;
+  return result;
 }
 
 static void tcpnodelay(struct Curl_cfilter *cf,
@@ -1087,18 +1092,19 @@ static void set_local_ip(struct Curl_cfilter *cf,
     /* TFTP does not connect, so it cannot get the IP like this */
     struct Curl_sockaddr_storage ssloc;
     curl_socklen_t slen = sizeof(struct Curl_sockaddr_storage);
-    VERBOSE(char buffer[STRERROR_LEN]);
 
     memset(&ssloc, 0, sizeof(ssloc));
     if(getsockname(ctx->sock, (struct sockaddr *)&ssloc, &slen)) {
+      VERBOSE(char buffer[STRERROR_LEN]);
       VERBOSE(int sockerr = SOCKERRNO);
       infof(data, "getsockname() failed with errno %d: %s",
             sockerr, curlx_strerror(sockerr, buffer, sizeof(buffer)));
     }
-    else if(!sockaddr2string((struct sockaddr *)&ssloc, slen,
-                             ctx->ip.local_ip, &ctx->ip.local_port)) {
-      infof(data, "ssloc inet_ntop() failed with errno %d: %s",
-            errno, curlx_strerror(errno, buffer, sizeof(buffer)));
+    else {
+      CURLcode result = sockaddr2string((struct sockaddr *)&ssloc, slen,
+                                        ctx->ip.local_ip, &ctx->ip.local_port);
+      if(result)
+        infof(data, "ssloc inet_ntop() failed with %d", (int)result);
     }
   }
 #else
@@ -1110,21 +1116,17 @@ static CURLcode set_remote_ip(struct Curl_cfilter *cf,
                               struct Curl_easy *data)
 {
   struct cf_socket_ctx *ctx = cf->ctx;
+  CURLcode result;
 
   /* store remote address and port used in this connection attempt */
   ctx->ip.transport = ctx->transport;
-  if(!sockaddr2string(&ctx->addr.curl_sa_addr,
-                      (curl_socklen_t)ctx->addr.addrlen,
-                      ctx->ip.remote_ip, &ctx->ip.remote_port)) {
-    char buffer[STRERROR_LEN];
-
-    /* using bare errno instead of SOCKERRNO is safe here, because
-       sockaddr2string() calls curlx_inet_ntop(), and they both report failures
-       via errno (even on Windows builds). */
-    ctx->sockerr = errno;
+  result = sockaddr2string(&ctx->addr.curl_sa_addr,
+                           (curl_socklen_t)ctx->addr.addrlen,
+                           ctx->ip.remote_ip, &ctx->ip.remote_port);
+  if(result) {
+    ctx->sockerr = SOCKEAFNOSUPPORT;
     /* malformed address or bug in inet_ntop, try next address */
-    failf(data, "curl_sa_addr inet_ntop() failed with errno %d: %s",
-          errno, curlx_strerror(errno, buffer, sizeof(buffer)));
+    failf(data, "curl_sa_addr inet_ntop() failed with %d", (int)result);
     return CURLE_FAILED_INIT;
   }
   return CURLE_OK;
@@ -2156,7 +2158,7 @@ static void cf_tcp_set_accepted_remote_ip(struct Curl_cfilter *cf,
 {
   struct cf_socket_ctx *ctx = cf->ctx;
 #ifdef HAVE_GETPEERNAME
-  char buffer[STRERROR_LEN];
+  CURLcode result;
   struct Curl_sockaddr_storage ssrem;
   curl_socklen_t plen;
 
@@ -2165,15 +2167,16 @@ static void cf_tcp_set_accepted_remote_ip(struct Curl_cfilter *cf,
   plen = sizeof(ssrem);
   memset(&ssrem, 0, plen);
   if(getpeername(ctx->sock, (struct sockaddr *)&ssrem, &plen)) {
+    char buffer[STRERROR_LEN];
     int sockerr = SOCKERRNO;
     failf(data, "getpeername() failed with errno %d: %s",
           sockerr, curlx_strerror(sockerr, buffer, sizeof(buffer)));
     return;
   }
-  if(!sockaddr2string((struct sockaddr *)&ssrem, plen,
-                      ctx->ip.remote_ip, &ctx->ip.remote_port)) {
-    failf(data, "ssrem inet_ntop() failed with errno %d: %s",
-          errno, curlx_strerror(errno, buffer, sizeof(buffer)));
+  result = sockaddr2string((struct sockaddr *)&ssrem, plen,
+                            ctx->ip.remote_ip, &ctx->ip.remote_port);
+  if(result) {
+    failf(data, "ssrem inet_ntop() failed with %d", (int)result);
     return;
   }
 #else
diff --git a/lib/curlx/inet_ntop.c b/lib/curlx/inet_ntop.c
index 7f6028a791..ed06314520 100644
--- a/lib/curlx/inet_ntop.c
+++ b/lib/curlx/inet_ntop.c
@@ -48,12 +48,12 @@
 /*
  * Format an IPv4 address, more or less like inet_ntop().
  *
- * Returns `dst' (as a const)
+ * Returns CURLcode.
  * Note:
  *  - uses no static variables
  *  - takes an unsigned char* not an in_addr as input
  */
-static char *inet_ntop4(const unsigned char *src, char *dst, size_t size)
+static CURLcode inet_ntop4(const unsigned char *src, char *dst, size_t size)
 {
   char tmp[sizeof("255.255.255.255")];
   size_t len;
@@ -68,22 +68,16 @@ static char *inet_ntop4(const unsigned char *src, char *dst, size_t size)
            ((int)((unsigned char)src[3])) & 0xff);
 
   len = strlen(tmp);
-  if(len == 0 || len >= size) {
-#ifdef USE_WINSOCK
-    errno = WSAEINVAL;
-#else
-    errno = ENOSPC;
-#endif
-    return NULL;
-  }
+  if(len == 0 || len >= size)
+    return CURLE_TOO_LARGE;
   curlx_strcopy(dst, size, tmp, len);
-  return dst;
+  return CURLE_OK;
 }
 
 /*
  * Convert IPv6 binary address into presentation (printable) format.
  */
-static char *inet_ntop6(const unsigned char *src, char *dst, size_t size)
+static CURLcode inet_ntop6(const unsigned char *src, char *dst, size_t size)
 {
   /*
    * Note that int32_t and int16_t need only be "at least" large enough
@@ -152,9 +146,9 @@ static char *inet_ntop6(const unsigned char *src, char *dst, size_t size)
      */
     if(i == 6 && best.base == 0 &&
        (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
-      if(!inet_ntop4(src + 12, tp, sizeof(tmp) - (tp - tmp))) {
-        return NULL;
-      }
+      CURLcode result = inet_ntop4(src + 12, tp, sizeof(tmp) - (tp - tmp));
+      if(result)
+        return result;
       tp += strlen(tp);
       break;
     }
@@ -181,31 +175,18 @@ static char *inet_ntop6(const unsigned char *src, char *dst, size_t size)
     *tp++ = ':';
 
   /* Check for overflow, copy, and we are done. */
-  if((size_t)(tp - tmp) >= size) {
-#ifdef USE_WINSOCK
-    errno = WSAEINVAL;
-#else
-    errno = ENOSPC;
-#endif
-    return NULL;
-  }
-
+  if((size_t)(tp - tmp) >= size)
+    return CURLE_TOO_LARGE;
   curlx_strcopy(dst, size, tmp, tp - tmp);
-  return dst;
+  return CURLE_OK;
 }
 
 /*
  * Convert a network format address to presentation format.
  *
- * Returns pointer to presentation format address (`buf').
- * Returns NULL on error and errno set with the specific
- * error, EAFNOSUPPORT or ENOSPC.
- *
- * On Windows we store the error in the thread errno, not in the Winsock error
- * code. This is to avoid losing the actual last Winsock error. When this
- * function returns NULL, check errno not SOCKERRNO.
+ * Copies result to 'buf' and returns CURLcode.
  */
-char *curlx_inet_ntop(int af, const void *src, char *buf, size_t size)
+CURLcode curlx_inet_ntop(int af, const void *src, char *buf, size_t size)
 {
   switch(af) {
   case AF_INET:
@@ -213,7 +194,6 @@ char *curlx_inet_ntop(int af, const void *src, char *buf, size_t size)
   case AF_INET6:
     return inet_ntop6((const unsigned char *)src, buf, size);
   default:
-    errno = SOCKEAFNOSUPPORT;
-    return NULL;
+    return CURLE_UNSUPPORTED_PROTOCOL;
   }
 }
diff --git a/lib/curlx/inet_ntop.h b/lib/curlx/inet_ntop.h
index 8f4c636d69..f0abeb80b7 100644
--- a/lib/curlx/inet_ntop.h
+++ b/lib/curlx/inet_ntop.h
@@ -25,6 +25,6 @@
  ***************************************************************************/
 #include "curl_setup.h"
 
-char *curlx_inet_ntop(int af, const void *src, char *buf, size_t size);
+CURLcode curlx_inet_ntop(int af, const void *src, char *buf, size_t size);
 
 #endif /* HEADER_CURL_INET_NTOP_H */
diff --git a/lib/ftp.c b/lib/ftp.c
index 1e17cb3467..3a4859d188 100644
--- a/lib/ftp.c
+++ b/lib/ftp.c
@@ -1022,7 +1022,7 @@ static CURLcode ftp_port_default_host(struct Curl_easy *data,
   struct sockaddr_in6 * const sa6 = (void *)sa;
 #endif
   char buffer[STRERROR_LEN];
-  const char *r;
+  CURLcode result;
 
   *sslenp = sizeof(*ss);
   if(getsockname(conn->sock[FIRSTSOCKET], sa, sslenp)) {
@@ -1033,14 +1033,14 @@ static CURLcode ftp_port_default_host(struct Curl_easy *data,
   switch(sa->sa_family) {
 #ifdef USE_IPV6
   case AF_INET6:
-    r = curlx_inet_ntop(sa->sa_family, &sa6->sin6_addr, hbuf, hbuflen);
+    result = curlx_inet_ntop(sa->sa_family, &sa6->sin6_addr, hbuf, hbuflen);
     break;
 #endif
   default:
-    r = curlx_inet_ntop(sa->sa_family, &sa4->sin_addr, hbuf, hbuflen);
+    result = curlx_inet_ntop(sa->sa_family, &sa4->sin_addr, hbuf, hbuflen);
     break;
   }
-  if(!r)
+  if(result)
     return CURLE_FTP_PORT_FAILED;
 
   *hostp = hbuf;
diff --git a/lib/if2ip.c b/lib/if2ip.c
index 5ae256e13c..9a9fbe7691 100644
--- a/lib/if2ip.c
+++ b/lib/if2ip.c
@@ -112,9 +112,9 @@ if2ip_result_t Curl_if2ip(int af,
         if(iface->ifa_addr->sa_family == af) {
           if(curl_strequal(iface->ifa_name, interf)) {
             void *addr;
-            const char *ip;
             char scope[12] = "";
             char ipstr[64];
+            CURLcode result;
 #ifdef USE_IPV6
             if(af == AF_INET6) {
 #ifdef HAVE_SOCKADDR_IN6_SIN6_SCOPE_ID
@@ -155,8 +155,8 @@ if2ip_result_t Curl_if2ip(int af,
               addr =
                 &((struct sockaddr_in *)(void *)iface->ifa_addr)->sin_addr;
             res = IF2IP_FOUND;
-            ip = curlx_inet_ntop(af, addr, ipstr, sizeof(ipstr));
-            curl_msnprintf(buf, buf_size, "%s%s", ip, scope);
+            result = curlx_inet_ntop(af, addr, ipstr, sizeof(ipstr));
+            curl_msnprintf(buf, buf_size, "%s%s", result ? "" : ipstr, scope);
             break;
           }
         }
@@ -188,7 +188,7 @@ if2ip_result_t Curl_if2ip(int af,
   struct sockaddr_in *s;
   curl_socket_t dummy;
   size_t len;
-  const char *r;
+  CURLcode result;
 
 #ifdef USE_IPV6
   (void)remote_scope;
@@ -228,10 +228,10 @@ if2ip_result_t Curl_if2ip(int af,
 
   s = (struct sockaddr_in *)(void *)&req.ifr_addr;
   memcpy(&in, &s->sin_addr, sizeof(in));
-  r = curlx_inet_ntop(s->sin_family, &in, buf, buf_size);
+  result = curlx_inet_ntop(s->sin_family, &in, buf, buf_size);
 
   sclose(dummy);
-  if(!r)
+  if(result)
     return IF2IP_NOT_FOUND;
   return IF2IP_FOUND;
 }
diff --git a/lib/urlapi.c b/lib/urlapi.c
index 1b498e95d0..e787773ced 100644
--- a/lib/urlapi.c
+++ b/lib/urlapi.c
@@ -467,7 +467,7 @@ UNITTEST CURLUcode ipv6_parse(struct Curl_URL *u, char *hostname,
     hostname[hlen] = 0; /* end the address there */
     if(curlx_inet_pton(AF_INET6, hostname, dest) != 1)
       return CURLUE_BAD_IPV6;
-    if(curlx_inet_ntop(AF_INET6, dest, hostname, hlen + 1)) {
+    if(!curlx_inet_ntop(AF_INET6, dest, hostname, hlen + 1)) {
       hlen = strlen(hostname); /* might be shorter now */
       hostname[hlen + 1] = 0;
     }
diff --git a/lib/vdns/httpsrr.c b/lib/vdns/httpsrr.c
index 29c78a333b..98a3c89496 100644
--- a/lib/vdns/httpsrr.c
+++ b/lib/vdns/httpsrr.c
@@ -82,7 +82,7 @@ static CURLcode httpsrr_print_addr(struct dynbuf *dyn,
   CURLcode result = CURLE_OK;
 
   for(i = 0; (i < (total_len / alen)) && !result; ++i) {
-    if(!curlx_inet_ntop(ai_family, addr + (i * alen), buf, sizeof(buf)))
+    if(curlx_inet_ntop(ai_family, addr + (i * alen), buf, sizeof(buf)))
       result = curlx_dyn_add(dyn, "<error parsing address>");
     else
       result = curlx_dyn_addf(dyn, "%s%s", sep, buf);
diff --git a/tests/server/dnsd.c b/tests/server/dnsd.c
index 62cbb8d9cf..c2d01c0aaa 100644
--- a/tests/server/dnsd.c
+++ b/tests/server/dnsd.c
@@ -606,6 +606,7 @@ static int dnsd_make_answer(struct blob *blob, int query_id,
   };
   uint16_t ancount = 0;
   unsigned char rcode = 0;
+  CURLcode result;
 
   /* read once per incoming query, which is probably more than one
      per test case */
@@ -656,12 +657,11 @@ static int dnsd_make_answer(struct blob *blob, int query_id,
   case QTYPE_A:
     for(a = 0; !rcode && (a < ancount_a); a++) {
       const unsigned char *store = ipv4_pref;
-      const char *ip;
       if(add_answer(blob, store, sizeof(ipv4_pref), QTYPE_A))
         return 1;
-      ip = curlx_inet_ntop(AF_INET, store, addrbuf, sizeof(addrbuf));
-      logmsg("[%d] response A (%x) '%s'", query_id, (unsigned int)QTYPE_A,
-             ip ? ip : "(null)");
+      result = curlx_inet_ntop(AF_INET, store, addrbuf, sizeof(addrbuf));
+      logmsg("[%d] response A (%x) '%s' (%d)", query_id,
+             (unsigned int)QTYPE_A, result ? "?" : addrbuf, (int)result);
     }
     if(!ancount_a)
       logmsg("[%d] response A empty", query_id);
@@ -669,12 +669,11 @@ static int dnsd_make_answer(struct blob *blob, int query_id,
   case QTYPE_AAAA:
     for(a = 0; !rcode && (a < ancount_aaaa); a++) {
       const unsigned char *store = ipv6_pref;
-      const char *ip;
       if(add_answer(blob, store, sizeof(ipv6_pref), QTYPE_AAAA))
         return 1;
-      ip = curlx_inet_ntop(AF_INET6, store, addrbuf, sizeof(addrbuf));
-      logmsg("[%d] response AAAA (%x) '%s'", query_id,
-             (unsigned int)QTYPE_AAAA, ip ? ip : "(null)");
+      result = curlx_inet_ntop(AF_INET6, store, addrbuf, sizeof(addrbuf));
+      logmsg("[%d] response AAAA (%x) '%s' (%d)", query_id,
+             (unsigned int)QTYPE_AAAA, result ? "?" : addrbuf, (int)result);
     }
     if(!ancount_aaaa)
       logmsg("[%d] response AAAA empty", query_id);
diff --git a/tests/unit/unit1607.c b/tests/unit/unit1607.c
index 2b55621340..72df3808ca 100644
--- a/tests/unit/unit1607.c
+++ b/tests/unit/unit1607.c
@@ -147,8 +147,8 @@ static CURLcode test_unit1607(const char *arg)
       if(tests[i].address[j] == &skip)
         continue;
 
-      if(addr && !sockaddr2string(addr->ai_addr, addr->ai_addrlen,
-                                  ipaddress, &port)) {
+      if(addr && sockaddr2string(addr->ai_addr, addr->ai_addrlen,
+                                 ipaddress, &port)) {
         curl_mfprintf(stderr, "%s:%d tests[%zu] failed. "
                       "getaddressinfo failed.\n",
                       __FILE__, __LINE__, i);
diff --git a/tests/unit/unit1609.c b/tests/unit/unit1609.c
index d7970a5cc6..076bf21499 100644
--- a/tests/unit/unit1609.c
+++ b/tests/unit/unit1609.c
@@ -146,8 +146,8 @@ static CURLcode test_unit1609(const char *arg)
       if(!addr && !tests[i].address[j])
         break;
 
-      if(addr && !sockaddr2string(addr->ai_addr, addr->ai_addrlen,
-                                  ipaddress, &port)) {
+      if(addr && sockaddr2string(addr->ai_addr, addr->ai_addrlen,
+                                 ipaddress, &port)) {
         curl_mfprintf(stderr,
                       "%s:%d tests[%zu] failed. Curl_addr2string failed.\n",
                       __FILE__, __LINE__, i);
diff --git a/tests/unit/unit1961.c b/tests/unit/unit1961.c
index 338eeb176b..1aa28a25bf 100644
--- a/tests/unit/unit1961.c
+++ b/tests/unit/unit1961.c
@@ -48,8 +48,6 @@ static int test_ntop(void)
   char ipv4res[sizeof("255.255.255.255")];
   unsigned char ipv6a[26];
   unsigned char ipv4a[5];
-  const char *ipv6ptr = 0;
-  const char *ipv4ptr = 0;
 
   ipv4res[0] = '\0';
   ipv4a[0] = 0xc0;
@@ -57,12 +55,9 @@ static int test_ntop(void)
   ipv4a[2] = 0x64;
   ipv4a[3] = 0x01;
   ipv4a[4] = 0x01;
-  ipv4ptr = curlx_inet_ntop(AF_INET, ipv4a, ipv4res, sizeof(ipv4res));
-  if(!ipv4ptr)
+  if(curlx_inet_ntop(AF_INET, ipv4a, ipv4res, sizeof(ipv4res)))
     return 1; /* fail */
-  if(ipv4ptr != ipv4res)
-    return 1; /* fail */
-  if(!ipv4ptr[0])
+  if(!ipv4res[0])
     return 1; /* fail */
   if(memcmp(ipv4res, "192.168.100.1", 13))
     return 1; /* fail */
@@ -80,12 +75,9 @@ static int test_ntop(void)
   ipv6a[14] = 0x76;
   ipv6a[15] = 0xc8;
   ipv6a[25] = 0x01;
-  ipv6ptr = curlx_inet_ntop(AF_INET6, ipv6a, ipv6res, sizeof(ipv6res));
-  if(!ipv6ptr)
+  if(curlx_inet_ntop(AF_INET6, ipv6a, ipv6res, sizeof(ipv6res)))
     return 1; /* fail */
-  if(ipv6ptr != ipv6res)
-    return 1; /* fail */
-  if(!ipv6ptr[0])
+  if(!ipv6res[0])
     return 1; /* fail */
   if(memcmp(ipv6res, "fe80::214:4fff:fe0b:76c8", 24))
     return 1; /* fail */
@@ -96,12 +88,9 @@ static int test_ntop(void)
   ipv6a[13] = 0x0;
   ipv6a[14] = 0x0;
   ipv6a[15] = 0x01;
-  ipv6ptr = curlx_inet_ntop(AF_INET6, ipv6a, ipv6res, sizeof(ipv6res));
-  if(!ipv6ptr)
+  if(curlx_inet_ntop(AF_INET6, ipv6a, ipv6res, sizeof(ipv6res)))
     return 1; /* fail */
-  if(ipv6ptr != ipv6res)
-    return 1; /* fail */
-  if(!ipv6ptr[0])
+  if(!ipv6res[0])
     return 1; /* fail */
   if(memcmp(ipv6res, "::127.0.0.1", 11))
     return 1; /* fail */