diff --git a/ports/esp8266/boards/GENERIC_512K/_boot.py b/ports/esp8266/boards/GENERIC_512K/_boot.py
new file mode 100644
index 0000000000..1a55cfd36c
--- /dev/null
+++ b/ports/esp8266/boards/GENERIC_512K/_boot.py
@@ -0,0 +1,3 @@
+import gc
+
+gc.threshold((gc.mem_free() + gc.mem_alloc()) // 4)
diff --git a/ports/esp8266/boards/GENERIC_512K/manifest.py b/ports/esp8266/boards/GENERIC_512K/manifest.py
index e7ab8ad535..5674f280b5 100644
--- a/ports/esp8266/boards/GENERIC_512K/manifest.py
+++ b/ports/esp8266/boards/GENERIC_512K/manifest.py
@@ -1,3 +1,4 @@
+freeze("$(BOARD_DIR)", "_boot.py", opt=3)
 freeze("$(PORT_DIR)/modules", ("apa102.py", "neopixel.py", "ntptime.py", "port_diag.py"))
 freeze("$(MPY_DIR)/drivers/dht", "dht.py")
 freeze("$(MPY_DIR)/drivers/onewire")