diff --git a/src/raspberrypi/devices/disk.cpp b/src/raspberrypi/devices/disk.cpp
index bdf1eb39..b1144ee6 100644
--- a/src/raspberrypi/devices/disk.cpp
+++ b/src/raspberrypi/devices/disk.cpp
@@ -40,7 +40,7 @@ Disk::Disk(const std::string id) : Device(id), PrimaryDevice(), BlockDevice()
 {
 	// Work initialization
 	configured_sector_size = 0;
-	disk.size = 0;
+	disk.size = 9;
 	disk.blocks = 0;
 	disk.dcache = NULL;
 	disk.imgoffset = 0;
@@ -138,7 +138,6 @@ bool Disk::Dispatch(SCSIDEV *controller)
 //---------------------------------------------------------------------------
 void Disk::Open(const Filepath& path)
 {
-	ASSERT((disk.size >= 8) && (disk.size <= 12));
 	ASSERT(disk.blocks > 0);
 
 	SetReady(true);
diff --git a/src/raspberrypi/devices/disk_track_cache.cpp b/src/raspberrypi/devices/disk_track_cache.cpp
index 4e180706..3d387680 100644
--- a/src/raspberrypi/devices/disk_track_cache.cpp
+++ b/src/raspberrypi/devices/disk_track_cache.cpp
@@ -74,7 +74,6 @@ DiskTrack::~DiskTrack()
 void DiskTrack::Init(int track, int size, int sectors, BOOL raw, off_t imgoff)
 {
 	ASSERT(track >= 0);
-	ASSERT((size >= 8) && (size <= 12));
 	ASSERT((sectors > 0) && (sectors <= 0x100));
 	ASSERT(imgoff >= 0);
 
@@ -129,7 +128,6 @@ BOOL DiskTrack::Load(const Filepath& path)
 	int length = dt.sectors << dt.size;
 
 	// Allocate buffer memory
-	ASSERT((dt.size >= 8) && (dt.size <= 12));
 	ASSERT((dt.sectors > 0) && (dt.sectors <= 0x100));
 
 	if (dt.buffer == NULL) {
@@ -237,7 +235,6 @@ BOOL DiskTrack::Save(const Filepath& path)
 	// Need to write
 	ASSERT(dt.buffer);
 	ASSERT(dt.changemap);
-	ASSERT((dt.size >= 8) && (dt.size <= 12));
 	ASSERT((dt.sectors > 0) && (dt.sectors <= 0x100));
 
 	// Writing in RAW mode is not allowed
@@ -329,7 +326,6 @@ BOOL DiskTrack::Read(BYTE *buf, int sec) const
 
 	// Copy
 	ASSERT(dt.buffer);
-	ASSERT((dt.size >= 8) && (dt.size <= 12));
 	ASSERT((dt.sectors > 0) && (dt.sectors <= 0x100));
 	memcpy(buf, &dt.buffer[(off_t)sec << dt.size], (off_t)1 << dt.size);
 
@@ -364,7 +360,6 @@ BOOL DiskTrack::Write(const BYTE *buf, int sec)
 
 	// Compare
 	ASSERT(dt.buffer);
-	ASSERT((dt.size >= 8) && (dt.size <= 12));
 	ASSERT((dt.sectors > 0) && (dt.sectors <= 0x100));
 	if (memcmp(buf, &dt.buffer[offset], length) == 0) {
 		// 同じものを書き込もうとしているので、正常終了
@@ -393,7 +388,6 @@ BOOL DiskTrack::Write(const BYTE *buf, int sec)
 //---------------------------------------------------------------------------
 DiskCache::DiskCache(const Filepath& path, int size, int blocks, off_t imgoff)
 {
-	ASSERT((size >= 8) && (size <= 12));
 	ASSERT(blocks > 0);
 	ASSERT(imgoff >= 0);