diff --git a/include/flash.h b/include/flash.h
index f06e66e..09efde3 100644
--- a/include/flash.h
+++ b/include/flash.h
@@ -12,12 +12,14 @@ struct flash_ops {
 	int (* write)(struct flash_dev *dev, uint32_t addr, const void *data,
 		size_t len);
 	int (* copy)(struct flash_dev *dev, uint32_t dst, uint32_t src, size_t len);
-	int (* erase)(struct flash_dev *dev, uint32_t addr, size_t block_size);
+	int (* erase)(struct flash_dev *dev, uint32_t addr);
 };
 
 struct flash_dev {
 	struct flash_ops *ops;
 	void *priv;
+	uint8_t log2_page_size;
+	uint8_t log2_block_size;
 };
 
 struct flash_dev *flash_probe(void);
@@ -28,4 +30,4 @@ int flash_read(struct flash_dev *dev, uint32_t addr, void *data, size_t len);
 int flash_write(struct flash_dev *dev, uint32_t addr, const void *data,
 	size_t len);
 int flash_copy(struct flash_dev *dev, uint32_t dst, uint32_t src, size_t len);
-int flash_erase(struct flash_dev *dev, uint32_t addr, size_t block_size);
+int flash_erase(struct flash_dev *dev, uint32_t addr, size_t len);
diff --git a/source/core/flash.c b/source/core/flash.c
index e6f7273..76d855d 100644
--- a/source/core/flash.c
+++ b/source/core/flash.c
@@ -44,10 +44,17 @@ int flash_copy(struct flash_dev *dev, uint32_t dst, uint32_t src, size_t len)
 	return dev->ops->copy(dev, dst, src, len);
 }
 
-int flash_erase(struct flash_dev *dev, uint32_t addr, size_t block_size)
+int flash_erase(struct flash_dev *dev, uint32_t addr, size_t len)
 {
 	if (!dev)
 		return -1;
 
-	return dev->ops->erase(dev, addr, block_size);
+	while (len--) {
+		if (dev->ops->erase(dev, addr) < 0)
+			return -1;
+
+		++addr;
+	}
+
+	return 0;
 }
diff --git a/source/drivers/sandbox_flash.c b/source/drivers/sandbox_flash.c
index 94531ba..8a23e72 100644
--- a/source/drivers/sandbox_flash.c
+++ b/source/drivers/sandbox_flash.c
@@ -25,7 +25,7 @@ static int stdio_flash_write(struct flash_dev *dev, uint32_t addr,
 	const void *data, size_t len);
 static int stdio_flash_copy(struct flash_dev *dev, uint32_t dst, uint32_t src,
 	size_t len);
-static int stdio_flash_erase(struct flash_dev *dev, uint32_t addr, size_t block_size);
+static int stdio_flash_erase(struct flash_dev *dev, uint32_t addr);
 
 static struct flash_ops stdio_flash_ops = {
 	.get_size = stdio_flash_get_size,
@@ -99,17 +99,12 @@ static int stdio_flash_copy(struct flash_dev *dev, uint32_t dst, uint32_t src,
 	return 0;
 }
 
-static int stdio_flash_erase(struct flash_dev *dev, uint32_t addr,
-	size_t block_size)
+static int stdio_flash_erase(struct flash_dev *dev, uint32_t addr)
 {
 	struct stdio_flash_priv *priv = dev->priv;
-	size_t log2_block_size = ilog2(block_size);
 
-	if (block_size != (UINT32_C(1) << log2_block_size))
-		return -1;
-
-	memset(priv->data + (addr << log2_block_size), 0xff,
-		(1 << log2_block_size));
+	memset(priv->data + (addr << dev->log2_block_size), 0xff,
+		1 << dev->log2_block_size);
 
 	return 0;
 }
@@ -140,6 +135,8 @@ struct flash_dev *flash_probe(void)
 
 	dev->priv = priv;
 	dev->ops = &stdio_flash_ops;
+	dev->log2_page_size = ilog2(1);
+	dev->log2_block_size = ilog2(4 * KIB);
 
 	return dev;
 
diff --git a/source/ftl/dev.c b/source/ftl/dev.c
index 1d9f571..b13753b 100644
--- a/source/ftl/dev.c
+++ b/source/ftl/dev.c
@@ -1,8 +1,10 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include <bitops.h>
 #include <flash.h>
 #include <ftl.h>
+#include <macros.h>
 
 static size_t ftl_flash_get_size(struct flash_dev *dev);
 static size_t ftl_flash_get_capacity(struct flash_dev *dev);
@@ -10,8 +12,7 @@ static int ftl_flash_read(struct flash_dev *dev, uint32_t addr, void *data,
 	size_t len);
 static int ftl_flash_write(struct flash_dev *dev, uint32_t addr,
 	const void *data, size_t len);
-static int ftl_flash_erase(struct flash_dev *dev, uint32_t addr,
-	size_t block_size);
+static int ftl_flash_erase(struct flash_dev *dev, uint32_t addr);
 
 static struct flash_ops ftl_flash_ops = {
 	.get_size = ftl_flash_get_size,
@@ -56,14 +57,10 @@ static int ftl_flash_write(struct flash_dev *dev, uint32_t addr,
 	return ftl_write(map, addr, data);
 }
 
-static int ftl_flash_erase(struct flash_dev *dev, uint32_t addr,
-	size_t block_size)
+static int ftl_flash_erase(struct flash_dev *dev, uint32_t addr)
 {
 	struct ftl_map *map = dev->priv;
 
-	/* TODO */
-	(void)block_size;
-
 	return ftl_trim(map, addr);
 }
 
@@ -86,6 +83,8 @@ struct flash_dev *ftl_mount(struct flash_dev *raw_dev)
 
 	dev->ops = &ftl_flash_ops;
 	dev->priv = map;
+	dev->log2_page_size = ilog2(4 * KIB);
+	dev->log2_block_size = ilog2(4 * KIB);
 
 	return dev;
 
diff --git a/source/ftl/gc.c b/source/ftl/gc.c
index 365fb84..d8d8a72 100644
--- a/source/ftl/gc.c
+++ b/source/ftl/gc.c
@@ -125,6 +125,5 @@ int prepare_head(struct ftl_map *map)
 	if (free_tail(map) < 0)
 		return -1;
 
-	return flash_erase(map->dev, map->head >> log2_pages_per_block,
-		map->log2_block_size);
+	return flash_erase(map->dev, map->head, 1 << log2_pages_per_block);
 }