diff --git a/mongoose.c b/mongoose.c
index 6f71df5a..c820e0a2 100644
--- a/mongoose.c
+++ b/mongoose.c
@@ -828,7 +828,7 @@ static bool bsd_run(struct mg_bsd_cmd *cmd) {
       fd_set *w = cmd->op_select.w;
       fd_set *e = cmd->op_select.e;
       int fd, n = 0, want_read, want_write, want_error, ready;
-#if MG_ENABLE_BSD_PROTOTYPES
+#if defined(MG_BSD_SELECT_H)
       int i;
       __fd_mask bits;
       int bitsize = (int) (sizeof(bits) * 8);
@@ -841,7 +841,7 @@ static bool bsd_run(struct mg_bsd_cmd *cmd) {
       FD_ZERO(&rr);
       FD_ZERO(&ww);
       FD_ZERO(&ee);
-#if MG_ENABLE_BSD_PROTOTYPES
+#if defined(MG_BSD_SELECT_H)
       for (i = 0; i < (cmd->op_select.nfds + bitsize - 1) / bitsize; i++) {
         bits = 0;
         if (r != NULL) bits |= r->__fds_bits[i];
diff --git a/mongoose.h b/mongoose.h
index 13b1c4f0..3a927ae3 100644
--- a/mongoose.h
+++ b/mongoose.h
@@ -4995,7 +4995,6 @@ void mg_bsd_poll(struct mg_mgr *);
 typedef unsigned int socklen_t;
 typedef unsigned long nfds_t;
 typedef uint32_t in_addr_t;
-typedef unsigned long __fd_mask;
 struct in_addr { in_addr_t s_addr; };
 struct in6_addr { uint8_t s6_addr[16]; };
 struct sockaddr { uint16_t sa_family; char sa_data[14]; };
@@ -5032,11 +5031,12 @@ struct addrinfo {
 };
 struct pollfd { int fd; short events; short revents; };
 
+#if !defined(FD_SET) && !defined(FD_ZERO) && !defined(FD_ISSET)
+#define MG_BSD_SELECT_H
+typedef unsigned long __fd_mask;
 #ifndef FD_SETSIZE
 #define FD_SETSIZE 64
 #endif
-
-#ifndef FD_ZERO
 #define _NFDBITS ((int) sizeof(__fd_mask) * 8)
 #define _howmany(x, y) (((x) + ((y) - 1)) / (y))
 typedef struct fd_set {
diff --git a/src/bsd.c b/src/bsd.c
index 467cbeca..f301e10d 100644
--- a/src/bsd.c
+++ b/src/bsd.c
@@ -661,7 +661,7 @@ static bool bsd_run(struct mg_bsd_cmd *cmd) {
       fd_set *w = cmd->op_select.w;
       fd_set *e = cmd->op_select.e;
       int fd, n = 0, want_read, want_write, want_error, ready;
-#if MG_ENABLE_BSD_PROTOTYPES
+#if defined(MG_BSD_SELECT_H)
       int i;
       __fd_mask bits;
       int bitsize = (int) (sizeof(bits) * 8);
@@ -674,7 +674,7 @@ static bool bsd_run(struct mg_bsd_cmd *cmd) {
       FD_ZERO(&rr);
       FD_ZERO(&ww);
       FD_ZERO(&ee);
-#if MG_ENABLE_BSD_PROTOTYPES
+#if defined(MG_BSD_SELECT_H)
       for (i = 0; i < (cmd->op_select.nfds + bitsize - 1) / bitsize; i++) {
         bits = 0;
         if (r != NULL) bits |= r->__fds_bits[i];
diff --git a/src/bsd.h b/src/bsd.h
index d905dfd1..5a01f70c 100644
--- a/src/bsd.h
+++ b/src/bsd.h
@@ -63,7 +63,6 @@ void mg_bsd_poll(struct mg_mgr *);
 typedef unsigned int socklen_t;
 typedef unsigned long nfds_t;
 typedef uint32_t in_addr_t;
-typedef unsigned long __fd_mask;
 struct in_addr { in_addr_t s_addr; };
 struct in6_addr { uint8_t s6_addr[16]; };
 struct sockaddr { uint16_t sa_family; char sa_data[14]; };
@@ -100,11 +99,12 @@ struct addrinfo {
 };
 struct pollfd { int fd; short events; short revents; };
 
+#if !defined(FD_SET) && !defined(FD_ZERO) && !defined(FD_ISSET)
+#define MG_BSD_SELECT_H
+typedef unsigned long __fd_mask;
 #ifndef FD_SETSIZE
 #define FD_SETSIZE 64
 #endif
-
-#ifndef FD_ZERO
 #define _NFDBITS ((int) sizeof(__fd_mask) * 8)
 #define _howmany(x, y) (((x) + ((y) - 1)) / (y))
 typedef struct fd_set {