diff --git a/CMakeLists.txt b/CMakeLists.txt
index e64473f37..7592ac8b4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1525,6 +1525,9 @@ if (WIN32)
 		lib/plat/windows/windows-service.c
 		lib/plat/windows/windows-sockets.c
 		)
+	if (LWS_WITH_SYS_ASYNC_DNS)
+		list(APPEND SOURCES lib/plat/windows/windows-resolv.c)
+	endif()
 else()
 
 	if (LWS_PLAT_OPTEE)
diff --git a/lib/plat/windows/windows-resolv.c b/lib/plat/windows/windows-resolv.c
index 1cfbcc633..541cc0ae6 100644
--- a/lib/plat/windows/windows-resolv.c
+++ b/lib/plat/windows/windows-resolv.c
@@ -39,7 +39,7 @@
 lws_async_dns_server_check_t
 lws_plat_asyncdns_init(struct lws_context *context, lws_sockaddr46 *sa46)
 {
-	char	subkey[512], dhcpns[512], ns[512], value[128], *key =
+	char	subkey[512], value[128], *key =
 	"SYSTEM\\ControlSet001\\Services\\Tcpip\\Parameters\\Interfaces";
 	HKEY	hKey, hSub;
 	LONG	err;
@@ -59,7 +59,7 @@ lws_plat_asyncdns_init(struct lws_context *context, lws_sockaddr46 *sa46)
 		    &type, value, &len) == ERROR_SUCCESS ||
 		    RegQueryValueEx(hSub, "DhcpNameServer", 0,
 		    &type, value, &len) == ERROR_SUCCESS)) {
-			n = lws_sa46_parse_numeric_address(value, sa46)
+			n = lws_sa46_parse_numeric_address(value, sa46);
 			RegCloseKey(hSub);
 			RegCloseKey(hKey);
 			return n == 0 ? LADNS_CONF_SERVER_CHANGED :
diff --git a/lib/system/async-dns/async-dns-parse.c b/lib/system/async-dns/async-dns-parse.c
index 48bc56a79..c4068cfcb 100644
--- a/lib/system/async-dns/async-dns-parse.c
+++ b/lib/system/async-dns/async-dns-parse.c
@@ -122,7 +122,7 @@ again1:
 
 	ls++;
 
-	return ls - ols;
+	return lws_ptr_diff(ls, ols);
 }
 
 typedef int (*lws_async_dns_find_t)(const char *name, void *opaque,
@@ -160,7 +160,7 @@ lws_adns_iterate(lws_adns_q_t *q, const uint8_t *pkt, int len,
 	uint32_t ttl;
 
 	lws_strncpy(stack[0].name, expname, sizeof(stack[0].name));
-	stack[0].enl = strlen(expname);
+	stack[0].enl = (int)strlen(expname);
 
 start:
 	ansc = lws_ser_ru16be(pkt + DHO_NANSWERS);
@@ -583,11 +583,11 @@ lws_adns_parse_udp(lws_async_dns_t *dns, const uint8_t *pkt, size_t len)
 	 *  char []: copy of resolved name
 	 */
 
-	ncname = strlen(nmcname) + 1;
+	ncname = (int)strlen(nmcname) + 1;
 
 	est = sizeof(lws_adns_cache_t) + ncname;
 	if (lws_ser_ru16be(pkt + DHO_NANSWERS)) {
-		int ir = lws_adns_iterate(q, pkt, len, nmcname,
+		int ir = lws_adns_iterate(q, pkt, (int)len, nmcname,
 					  lws_async_dns_estimate, &est);
 		if (ir < 0)
 			goto fail_out;
@@ -599,7 +599,7 @@ lws_adns_parse_udp(lws_async_dns_t *dns, const uint8_t *pkt, size_t len)
 	/* but we want to create the cache entry against the original request */
 
 	nm = ((const char *)&q[1]) + DNS_MAX;
-	n = strlen(nm) + 1;
+	n = (int)strlen(nm) + 1;
 
 	lwsl_info("%s: create cache entry for %s, %zu\n", __func__, nm,
 			est - sizeof(lws_adns_cache_t));
@@ -632,7 +632,7 @@ lws_adns_parse_udp(lws_async_dns_t *dns, const uint8_t *pkt, size_t len)
 	 */
 
 	if (lws_ser_ru16be(pkt + DHO_NANSWERS) &&
-	    lws_adns_iterate(q, pkt, len, nmcname, lws_async_dns_store, &adst) < 0) {
+	    lws_adns_iterate(q, pkt, (int)len, nmcname, lws_async_dns_store, &adst) < 0) {
 		lws_free(c);
 		goto fail_out;
 	}
diff --git a/lib/system/async-dns/async-dns.c b/lib/system/async-dns/async-dns.c
index 81c34e0b9..c1332d14f 100644
--- a/lib/system/async-dns/async-dns.c
+++ b/lib/system/async-dns/async-dns.c
@@ -483,7 +483,7 @@ check_tid(struct lws_dll2 *d, void *user)
 {
 	lws_adns_q_t *q = lws_container_of(d, lws_adns_q_t, list);
 
-	return q->tid == (uint16_t)(long)user;
+	return q->tid == (uint16_t)(intptr_t)user;
 }
 
 int
@@ -502,7 +502,7 @@ lws_async_dns_get_new_tid(struct lws_context *context, lws_adns_q_t *q)
 			return -1;
 
 		if (lws_dll2_foreach_safe(&dns->waiting,
-					  (void *)(long)tid, check_tid))
+					  (void *)(intptr_t)tid, check_tid))
 			continue;
 
 		q->tid = tid;