diff -urN 2.3.0.orig/cores/esp8266/Esp.cpp 2.3.0/cores/esp8266/Esp.cpp
--- 2.3.0.orig/cores/esp8266/Esp.cpp	2016-06-21 10:06:45.000000000 +0200
+++ 2.3.0/cores/esp8266/Esp.cpp	2018-02-25 00:15:28.424217374 +0100
@@ -508,10 +508,28 @@
 }
 
 bool EspClass::flashWrite(uint32_t offset, uint32_t *data, size_t size) {
-    ets_isr_mask(FLASH_INT_MASK);
-    int rc = spi_flash_write(offset, (uint32_t*) data, size);
-    ets_isr_unmask(FLASH_INT_MASK);
-    return rc == 0;
+	static uint32_t flash_chip_id = 0;
+
+	if (flash_chip_id == 0)
+		flash_chip_id = getFlashChipId();
+	ets_isr_mask(FLASH_INT_MASK);
+	int rc;
+	uint32_t* ptr = data;
+	if ((flash_chip_id & 0x000000ff) == 0x85) { // 0x146085 PUYA
+		static uint32_t read_buf[SPI_FLASH_SEC_SIZE / 4];
+		rc = spi_flash_read(offset, read_buf, size);
+		if (rc != 0) {
+			ets_isr_unmask(FLASH_INT_MASK);
+			return false;
+		}
+		for (size_t i = 0; i < size / 4; ++i) {
+			read_buf[i] &= data[i];
+		}
+		ptr = read_buf;
+	}
+	rc = spi_flash_write(offset, ptr, size);
+	ets_isr_unmask(FLASH_INT_MASK);
+	return rc == 0;
 }
 
 bool EspClass::flashRead(uint32_t offset, uint32_t *data, size_t size) {