While ANET_ERR is -1, check syscall retval for -1 itself.

src/anet.c

@@ -496,7 +496,7 @@ int anetTcpAccept(char *err, int s, char *ip, size_t ip_len, int *port) {
     int fd;
     struct sockaddr_storage sa;
     socklen_t salen = sizeof(sa);
-    if ((fd = anetGenericAccept(err,s,(struct sockaddr*)&sa,&salen)) == ANET_ERR)
+    if ((fd = anetGenericAccept(err,s,(struct sockaddr*)&sa,&salen)) == -1)
         return ANET_ERR;
 
     if (sa.ss_family == AF_INET) {
@@ -515,7 +515,7 @@ int anetUnixAccept(char *err, int s) {
     int fd;
     struct sockaddr_un sa;
     socklen_t salen = sizeof(sa);
-    if ((fd = anetGenericAccept(err,s,(struct sockaddr*)&sa,&salen)) == ANET_ERR)
+    if ((fd = anetGenericAccept(err,s,(struct sockaddr*)&sa,&salen)) == -1)
         return ANET_ERR;
 
     return fd;