diff --git a/SerialFlash.h b/SerialFlash.h
index f51dc21..20d57d1 100644
--- a/SerialFlash.h
+++ b/SerialFlash.h
@@ -40,6 +40,7 @@ class SerialFlashChip
 	static bool begin(uint8_t pin = 6);
 	static uint32_t capacity(const uint8_t *id);
 	static uint32_t blockSize();
+	static uint32_t eraseSectorSize();
 	static void sleep();
 	static void wakeup();
 	static void readID(uint8_t *buf);
@@ -50,12 +51,11 @@ class SerialFlashChip
 	static void write(uint32_t addr, const void *buf, uint32_t len);
 	static void eraseAll();
 	static void eraseBlock(uint32_t addr);
+	static void eraseSector(uint32_t addr);
 
 	static SerialFlashFile open(const char *filename);
 	static bool create(const char *filename, uint32_t length, uint32_t align = 0);
-	static bool createErasable(const char *filename, uint32_t length) {
-		return create(filename, length, blockSize());
-	}
+	static bool createErasable(const char *filename, uint32_t length);
 	static bool exists(const char *filename);
 	static bool remove(const char *filename);
 	static bool remove(SerialFlashFile &file);
diff --git a/SerialFlashChip.cpp b/SerialFlashChip.cpp
index a07618b..1bbd253 100644
--- a/SerialFlashChip.cpp
+++ b/SerialFlashChip.cpp
@@ -46,6 +46,7 @@ static SPIClass& SPIPORT = SPI;
 #define FLAG_DIFF_SUSPEND	0x04	// uses 2 different suspend commands
 #define FLAG_MULTI_DIE		0x08	// multiple die, don't read cross 32M barrier
 #define FLAG_256K_BLOCKS	0x10	// has 256K erase blocks
+#define FLAG_SECTOR_ERASE   0x20	// has 4k erase sectors
 #define FLAG_DIE_MASK		0xC0	// top 2 bits count during multi-die erase
 
 void SerialFlashChip::wait(void)
@@ -288,6 +289,30 @@ void SerialFlashChip::eraseBlock(uint32_t addr)
 }
 
 
+void SerialFlashChip::eraseSector(uint32_t addr)
+{
+	uint8_t f = flags;
+	if (busy) wait();
+	SPIPORT.beginTransaction(SPICONFIG);
+	CSASSERT();
+	SPIPORT.transfer(0x06); // write enable command
+	CSRELEASE();
+	 delayMicroseconds(1);
+	CSASSERT();
+	if (f & FLAG_32BIT_ADDR) {
+		SPIPORT.transfer(0x20);
+		SPIPORT.transfer16(addr >> 16);
+		SPIPORT.transfer16(addr);
+	} else {
+		SPIPORT.transfer16(0x2000 | ((addr >> 16) & 255));
+		SPIPORT.transfer16(addr);
+	}
+	CSRELEASE();
+	SPIPORT.endTransaction();
+	busy = 2;
+}
+
+
 bool SerialFlashChip::ready()
 {
 	uint32_t status;
@@ -391,6 +416,9 @@ bool SerialFlashChip::begin(uint8_t pin)
 		// Micron requires busy checks with a different command
 		f |= FLAG_STATUS_CMD70; // TODO: all or just multi-die chips?
 	}
+	if (id[0] == ID0_WINBOND) {
+		f |= FLAG_SECTOR_ERASE;	
+	}
 	flags = f;
 	readID(id);
 	return true;
@@ -478,6 +506,13 @@ uint32_t SerialFlashChip::blockSize()
 	return 65536;
 }
 
+uint32_t SerialFlashChip::eraseSectorSize()
+{
+	if (flags & FLAG_SECTOR_ERASE) return 4096;
+	// everything else seems to have 64K sectors
+	return blockSize();
+}
+
 
 
 
diff --git a/SerialFlashDirectory.cpp b/SerialFlashDirectory.cpp
index d97d971..2d567b5 100644
--- a/SerialFlashDirectory.cpp
+++ b/SerialFlashDirectory.cpp
@@ -330,6 +330,14 @@ bool SerialFlashChip::create(const char *filename, uint32_t length, uint32_t ali
 	return true;
 }
 
+bool SerialFlashChip::createErasable(const char *filename, uint32_t length) {
+	uint32_t filesize = SerialFlash.eraseSectorSize();
+	while (length > filesize) {
+		filesize = filesize * 2;
+	}
+	return create(filename, length, filesize);
+}
+
 bool SerialFlashChip::readdir(char *filename, uint32_t strsize, uint32_t &filesize)
 {
 	uint32_t maxfiles, index, straddr;
@@ -381,13 +389,19 @@ bool SerialFlashChip::readdir(char *filename, uint32_t strsize, uint32_t &filesi
 
 void SerialFlashFile::erase()
 {
-	uint32_t i, blocksize;
-
-	blocksize = SerialFlash.blockSize();
-	if (address & (blocksize - 1)) return; // must begin on a block boundary
-	if (length & (blocksize - 1)) return;  // must be exact number of blocks
-	for (i=0; i < length; i += blocksize) {
-		SerialFlash.eraseBlock(address + i);
+	uint32_t i, blockSize, sectorSize;
+
+	blockSize = SerialFlash.blockSize();
+	sectorSize = SerialFlash.eraseSectorSize();
+
+	if (address & (sectorSize - 1)) return; // must begin on a block boundary
+	if (length & (sectorSize - 1)) return;  // must be exact number of blocks
+	for (i=0; i < length; i += sectorSize) {
+		if (sectorSize < blockSize) {
+			SerialFlash.eraseSector(address + i);
+		} else {
+			SerialFlash.eraseBlock(address + i);
+		}
 	}
 }