diff --git a/src/api/sockets.c b/src/api/sockets.c
index 35d1fc93..a23c7978 100644
--- a/src/api/sockets.c
+++ b/src/api/sockets.c
@@ -66,6 +66,10 @@
 #include "lwip/inet_chksum.h"
 #endif
 
+#if LWIP_COMPAT_SOCKETS == 2 && LWIP_POSIX_SOCKETS_IO_NAMES
+#include <stdarg.h>
+#endif
+
 #include <string.h>
 
 /* If the netconn API is not required publicly, then we include the necessary
@@ -3467,6 +3471,20 @@ lwip_fcntl(int s, int cmd, int val)
   return ret;
 }
 
+#if LWIP_COMPAT_SOCKETS == 2 && LWIP_POSIX_SOCKETS_IO_NAMES
+int
+fcntl(int s, int cmd, ...)
+{
+  va_list ap;
+  int val;
+
+  va_start(ap, cmd);
+  val = va_arg(ap, int);
+  va_end(ap);
+  return lwip_fcntl(s, cmd, val);
+}
+#endif
+
 const char *
 lwip_inet_ntop(int af, const void *src, char *dst, socklen_t size)
 {
diff --git a/src/include/lwip/sockets.h b/src/include/lwip/sockets.h
index 65e2ddbb..164f12b7 100644
--- a/src/include/lwip/sockets.h
+++ b/src/include/lwip/sockets.h
@@ -534,7 +534,7 @@ void lwip_socket_thread_cleanup(void); /* LWIP_NETCONN_SEM_PER_THREAD==1: destro
 #undef lwip_close
 #define lwip_close        close
 #define closesocket(s)    close(s)
-#define lwip_fcntl        fcntl
+int fcntl(int s, int cmd, ...);
 #define lwip_ioctl        ioctl
 #endif /* LWIP_POSIX_SOCKETS_IO_NAMES */
 #endif /* LWIP_COMPAT_SOCKETS == 2 */