diff --git a/lib/core-net/dummy-callback.c b/lib/core-net/dummy-callback.c
index 697e644f7..a45eee332 100644
--- a/lib/core-net/dummy-callback.c
+++ b/lib/core-net/dummy-callback.c
@@ -296,7 +296,8 @@ lws_callback_http_dummy(struct lws *wsi, enum lws_callback_reasons reason,
 	case LWS_CALLBACK_HTTP_BODY:
 		if (wsi->child_list) {
 			lwsl_user("%s: LWS_CALLBACK_HTTP_BODY: stashing %d\n", __func__, (int)len);
-			lws_buflist_append_segment(&wsi->http.buflist_post_body, in, len);
+			if (lws_buflist_append_segment(&wsi->http.buflist_post_body, in, len) < 0)
+				return -1;
 			lws_callback_on_writable(wsi->child_list);
 		}
 		break;
diff --git a/lib/core-net/private.h b/lib/core-net/private.h
index 351e32af1..11dbfb1cf 100644
--- a/lib/core-net/private.h
+++ b/lib/core-net/private.h
@@ -788,7 +788,7 @@ lws_hdr_simple_create(struct lws *wsi, enum lws_token_indexes h, const char *s);
 LWS_EXTERN int LWS_WARN_UNUSED_RESULT
 lws_ensure_user_space(struct lws *wsi);
 
-LWS_EXTERN int
+LWS_EXTERN int LWS_WARN_UNUSED_RESULT
 lws_change_pollfd(struct lws *wsi, int _and, int _or);
 
 #ifndef LWS_NO_SERVER
diff --git a/lib/core-net/service.c b/lib/core-net/service.c
index 96aaf2ab3..a14a303f8 100644
--- a/lib/core-net/service.c
+++ b/lib/core-net/service.c
@@ -204,7 +204,8 @@ user_service_go_again:
 	vwsi->handling_pollout = 0;
 
 	if (vwsi->leave_pollout_active)
-		lws_change_pollfd(wsi, 0, LWS_POLLOUT);
+		if (lws_change_pollfd(wsi, 0, LWS_POLLOUT))
+			goto bail_die;
 
 	return n;
 
diff --git a/lib/roles/cgi/cgi-server.c b/lib/roles/cgi/cgi-server.c
index ef2d26298..ea93815e3 100644
--- a/lib/roles/cgi/cgi-server.c
+++ b/lib/roles/cgi/cgi-server.c
@@ -184,9 +184,12 @@ lws_cgi(struct lws *wsi, const char * const *exec_array,
 		wsi->child_list = cgi->stdwsi[n];
 	}
 
-	lws_change_pollfd(cgi->stdwsi[LWS_STDIN], LWS_POLLIN, LWS_POLLOUT);
-	lws_change_pollfd(cgi->stdwsi[LWS_STDOUT], LWS_POLLOUT, LWS_POLLIN);
-	lws_change_pollfd(cgi->stdwsi[LWS_STDERR], LWS_POLLOUT, LWS_POLLIN);
+	if (lws_change_pollfd(cgi->stdwsi[LWS_STDIN], LWS_POLLIN, LWS_POLLOUT))
+		goto bail3;
+	if (lws_change_pollfd(cgi->stdwsi[LWS_STDOUT], LWS_POLLOUT, LWS_POLLIN))
+		goto bail3;
+	if (lws_change_pollfd(cgi->stdwsi[LWS_STDERR], LWS_POLLOUT, LWS_POLLIN))
+		goto bail3;
 
 	lwsl_debug("%s: fds in %d, out %d, err %d\n", __func__,
 		   cgi->stdwsi[LWS_STDIN]->desc.sockfd,
diff --git a/lib/roles/h1/ops-h1.c b/lib/roles/h1/ops-h1.c
index aa6a62599..1b13100c3 100644
--- a/lib/roles/h1/ops-h1.c
+++ b/lib/roles/h1/ops-h1.c
@@ -354,7 +354,8 @@ lws_h1_server_socket_service(struct lws *wsi, struct lws_pollfd *pollfd)
 		case 0:
 			lwsl_info("%s: read 0 len a\n", __func__);
 			wsi->seen_zero_length_recv = 1;
-			lws_change_pollfd(wsi, LWS_POLLIN, 0);
+			if (lws_change_pollfd(wsi, LWS_POLLIN, 0))
+				goto fail;
 #if !defined(LWS_WITHOUT_EXTENSIONS)
 			/*
 			 * autobahn requires us to win the race between close
@@ -635,7 +636,8 @@ rops_handle_POLLIN_h1(struct lws_context_per_thread *pt, struct lws *wsi,
 		 * and turn off our POLLIN
 		 */
 		wsi->client_rx_avail = 1;
-		lws_change_pollfd(wsi, LWS_POLLIN, 0);
+		if (lws_change_pollfd(wsi, LWS_POLLIN, 0))
+			return LWS_HPI_RET_PLEASE_CLOSE_ME;
 
 		//lwsl_notice("calling back %s\n", wsi->protocol->name);
 
diff --git a/lib/roles/h2/ops-h2.c b/lib/roles/h2/ops-h2.c
index 183f81c04..06b7810ea 100644
--- a/lib/roles/h2/ops-h2.c
+++ b/lib/roles/h2/ops-h2.c
@@ -235,7 +235,8 @@ drain:
 		 * and turn off our POLLIN
 		 */
 		wsi->client_rx_avail = 1;
-		lws_change_pollfd(wsi, LWS_POLLIN, 0);
+		if (lws_change_pollfd(wsi, LWS_POLLIN, 0))
+			return LWS_HPI_RET_PLEASE_CLOSE_ME;
 
 		/* let user code know, he'll usually ask for writeable
 		 * callback and drain / re-enable it there
@@ -1128,7 +1129,8 @@ next_child:
 	wsi2a = wsi->h2.child_list;
 	while (wsi2a) {
 		if (wsi2a->h2.requested_POLLOUT) {
-			lws_change_pollfd(wsi, 0, LWS_POLLOUT);
+			if (lws_change_pollfd(wsi, 0, LWS_POLLOUT))
+				return -1;
 			break;
 		}
 		wsi2a = wsi2a->h2.sibling_list;
diff --git a/lib/roles/http/client/client-handshake.c b/lib/roles/http/client/client-handshake.c
index 8a5c6a709..7ee4717f3 100644
--- a/lib/roles/http/client/client-handshake.c
+++ b/lib/roles/http/client/client-handshake.c
@@ -637,7 +637,11 @@ ads_known:
 			goto oom4;
 		}
 
-		lws_change_pollfd(wsi, 0, LWS_POLLIN);
+		if (lws_change_pollfd(wsi, 0, LWS_POLLIN)) {
+			compatible_close(wsi->desc.sockfd);
+			cce = "change_pollfd failed";
+			goto oom4;
+		}
 
 		/*
 		 * past here, we can't simply free the structs as error
diff --git a/lib/roles/http/compression/stream.c b/lib/roles/http/compression/stream.c
index 617750ad4..7acb58e9b 100644
--- a/lib/roles/http/compression/stream.c
+++ b/lib/roles/http/compression/stream.c
@@ -158,8 +158,9 @@ lws_http_compression_transform(struct lws *wsi, unsigned char *buf,
 		 * and switch to trying to process the head.
 		 */
 		if (buf && len) {
-			lws_buflist_append_segment(
-				&ctx->buflist_comp, buf, len);
+			if (lws_buflist_append_segment(
+					&ctx->buflist_comp, buf, len) < 0)
+				return -1;
 			lwsl_debug("%s: %p: adding %d to comp buflist\n",
 				   __func__,wsi, (int)len);
 		}
@@ -208,8 +209,9 @@ lws_http_compression_transform(struct lws *wsi, unsigned char *buf,
 		  * ...we were sending stuff from the caller directly and not
 		  * all of it got processed... stash on the buflist tail
 		  */
-		lws_buflist_append_segment(&ctx->buflist_comp,
-					   buf + ilen_iused, len - ilen_iused);
+		if (lws_buflist_append_segment(&ctx->buflist_comp,
+					   buf + ilen_iused, len - ilen_iused) < 0)
+			return -1;
 
 		lwsl_debug("%s: buffering %d unused comp input\n", __func__,
 			   (int)(len - ilen_iused));
diff --git a/lib/roles/raw-proxy/ops-raw-proxy.c b/lib/roles/raw-proxy/ops-raw-proxy.c
index 6957744d5..9deb9c137 100644
--- a/lib/roles/raw-proxy/ops-raw-proxy.c
+++ b/lib/roles/raw-proxy/ops-raw-proxy.c
@@ -56,7 +56,8 @@ rops_handle_POLLIN_raw_proxy(struct lws_context_per_thread *pt, struct lws *wsi,
 		case 0:
 			lwsl_info("%s: read 0 len\n", __func__);
 			wsi->seen_zero_length_recv = 1;
-			lws_change_pollfd(wsi, LWS_POLLIN, 0);
+			if (lws_change_pollfd(wsi, LWS_POLLIN, 0))
+				goto fail;
 
 			/*
 			 * we need to go to fail here, since it's the only
diff --git a/lib/roles/raw-skt/ops-raw-skt.c b/lib/roles/raw-skt/ops-raw-skt.c
index 939b2aefa..ff8140fbc 100644
--- a/lib/roles/raw-skt/ops-raw-skt.c
+++ b/lib/roles/raw-skt/ops-raw-skt.c
@@ -72,7 +72,8 @@ rops_handle_POLLIN_raw_skt(struct lws_context_per_thread *pt, struct lws *wsi,
 		case 0:
 			lwsl_info("%s: read 0 len\n", __func__);
 			wsi->seen_zero_length_recv = 1;
-			lws_change_pollfd(wsi, LWS_POLLIN, 0);
+			if (lws_change_pollfd(wsi, LWS_POLLIN, 0))
+				goto fail;
 
 			/*
 			 * we need to go to fail here, since it's the only