diff --git a/ports/esp8266/main.c b/ports/esp8266/main.c
index d1b88a8cec..d2d2c34ece 100644
--- a/ports/esp8266/main.c
+++ b/ports/esp8266/main.c
@@ -137,3 +137,17 @@ void __assert(const char *file, int line, const char *expr) {
     for (;;) {
     }
 }
+
+#if !MICROPY_DEBUG_PRINTERS
+// With MICROPY_DEBUG_PRINTERS disabled DEBUG_printf is not defined but it
+// is still needed by esp-open-lwip for debugging output, so define it here.
+#include <stdarg.h>
+int mp_vprintf(const mp_print_t *print, const char *fmt, va_list args);
+int DEBUG_printf(const char *fmt, ...) {
+    va_list ap;
+    va_start(ap, fmt);
+    int ret = mp_vprintf(&MICROPY_DEBUG_PRINTER_DEST, fmt, ap);
+    va_end(ap);
+    return ret;
+}
+#endif
diff --git a/ports/esp8266/mpconfigport_512k.h b/ports/esp8266/mpconfigport_512k.h
index b84c134792..dc97efd35d 100644
--- a/ports/esp8266/mpconfigport_512k.h
+++ b/ports/esp8266/mpconfigport_512k.h
@@ -5,6 +5,9 @@
 #undef MICROPY_EMIT_INLINE_XTENSA
 #define MICROPY_EMIT_INLINE_XTENSA      (0)
 
+#undef MICROPY_DEBUG_PRINTERS
+#define MICROPY_DEBUG_PRINTERS          (0)
+
 #undef MICROPY_ERROR_REPORTING
 #define MICROPY_ERROR_REPORTING         (MICROPY_ERROR_REPORTING_TERSE)