diff --git a/libports/lib/mk/lwip.mk b/libports/lib/mk/lwip.mk
index 1775a7333..b175abc43 100644
--- a/libports/lib/mk/lwip.mk
+++ b/libports/lib/mk/lwip.mk
@@ -27,7 +27,7 @@ SRC_C   += etharp.c
 
 LIBS     = thread cxx alarm signal libc timed_semaphore
 
-D_OPTS   = ERRNO SO_REUSE
+D_OPTS   = ERRNO SO_REUSE LWIP_SO_RCVBUF RECV_BUFSIZE_DEFAULT=8192
 D_OPTS  := $(addprefix -D,$(D_OPTS))
 CC_DEF  += $(D_OPTS)
 
diff --git a/libports/src/lib/libc_lwip/plugin.cc b/libports/src/lib/libc_lwip/plugin.cc
index d923bb339..4d580be44 100644
--- a/libports/src/lib/libc_lwip/plugin.cc
+++ b/libports/src/lib/libc_lwip/plugin.cc
@@ -321,10 +321,10 @@ int Plugin::fcntl(Libc::File_descriptor *sockfdo, int cmd, long val)
 	switch (cmd) {
 	case F_GETFL:
 	case F_SETFL:
-		result = lwip_fcntl(s, cmd, val);
+		result = lwip_fcntl(s, cmd, (val & O_NONBLOCK) ? -1 : O_NONBLOCK);
 		break;
 	default:
-		PERR("unsupported fcntl() request");
+		PERR("unsupported fcntl() request: %d", cmd);
 		break;
 	}