diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 1f859285..8fc36371 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -3,6 +3,7 @@ name: Build firmware
 on:
   push:
     branches: ['**']
+  pull_request:
 
 jobs:
   build:
diff --git a/httpd/httpd.c b/httpd/httpd.c
index 41a3fc65..fb9c678f 100644
--- a/httpd/httpd.c
+++ b/httpd/httpd.c
@@ -344,7 +344,7 @@ __xdata uint8_t *scan_header(__xdata uint8_t * __xdata p)
 
 	read_reg_timer(&now);
 
-	if (session) {
+	if (session && session_id[0]) {
 		if (now - last_session_use > session_timeout) {
 			dbg_string("Session expired\n");
 		} else {
diff --git a/machine.c b/machine.c
index aeb8d5bc..1c2fee14 100644
--- a/machine.c
+++ b/machine.c
@@ -1182,6 +1182,7 @@ __code const struct machine machine = {
 			0
 		},
 	},
+};
 #elif defined MACHINE_POE_2G080110GS
 __code const struct machine machine = {
 	.machine_name = "MokerLink POE-2G080110GS",
diff --git a/machine.h b/machine.h
index b6d4a825..14fc5c13 100644
--- a/machine.h
+++ b/machine.h
@@ -44,6 +44,7 @@
 // #define MACHINE_SWTG024AS_V2_0
 // #define MACHINE_FG_4GT_2SX_V2_0
 // #define MACHINE_FG_8GT_1SX
+// #define MACHINE_LIANGUO_HYWS_SGT0108S
 // #define MACHINE_POE_2G080110GS
 
 typedef struct {
diff --git a/rtl837x_flash.c b/rtl837x_flash.c
index 5f04c88a..2ec5bc3f 100644
--- a/rtl837x_flash.c
+++ b/rtl837x_flash.c
@@ -221,7 +221,9 @@ void flash_read_jedecid(void)
  */
 void flash_read_bulk(__xdata uint8_t *dst)
 {
-	short status;
+	if (!flash_region.len)
+		return;
+
 	flash_configure_sio();
 	while (flash_read_status() & STATUS_REG_BUSY_MASK);
 	flash_configure_mmio();
@@ -258,6 +260,9 @@ void flash_read_bulk(__xdata uint8_t *dst)
 
 void flash_read_security(void)
 {
+	if (!flash_region.len)
+		return;
+
 	flash_configure_sio();
 
 	while (flash_read_status() & STATUS_REG_BUSY_MASK);