diff --git a/Checkpoint.cpp b/Checkpoint.cpp
index 0a64395..9761ca9 100644
--- a/Checkpoint.cpp
+++ b/Checkpoint.cpp
@@ -233,7 +233,6 @@ Status cp_prepareCheckpoint() {
 }
 
 namespace {
-const int kBlockSize = 4096;
 const int kSectorSize = 512;
 
 typedef uint64_t sector_t;
@@ -247,6 +246,7 @@ struct log_entry {
 
 struct log_sector {
     uint32_t magic;
+    uint32_t block_size;
     uint32_t count;
     uint32_t sequence;
     uint64_t sector0;
@@ -308,20 +308,21 @@ void crc32(const void* data, size_t n_bytes, uint32_t* crc) {
     }
 }
 
-}  // namespace
-
-static void read(std::fstream& device, std::vector<log_entry> const& logs, sector_t sector,
-                 char* buffer) {
+void read(std::fstream& device, std::vector<log_entry> const& logs, sector_t sector, char* buffer,
+          uint32_t block_size) {
+    // Crude approach at first where we do this sector by sector and just scan
+    // the entire logs for remappings each time
     for (auto l = logs.rbegin(); l != logs.rend(); l++)
         if (sector >= l->source && (sector - l->source) * kSectorSize < l->size)
             sector = sector - l->source + l->dest;
 
     device.seekg(sector * kSectorSize);
-    device.read(buffer, kBlockSize);
+    device.read(buffer, block_size);
 }
 
-static std::vector<char> read(std::fstream& device, std::vector<log_entry> const& logs,
-                              bool validating, sector_t sector, uint32_t size) {
+// Read from the device as though we were restoring, even if we are validating
+std::vector<char> read(std::fstream& device, std::vector<log_entry> const& logs, bool validating,
+                       sector_t sector, uint32_t size, uint32_t block_size) {
     if (!validating) {
         std::vector<char> buffer(size);
         device.seekg(sector * kSectorSize);
@@ -329,16 +330,15 @@ static std::vector<char> read(std::fstream& device, std::vector<log_entry> const
         return buffer;
     }
 
-    // Crude approach at first where we do this sector by sector and just scan
-    // the entire logs for remappings each time
     std::vector<char> buffer(size);
-
-    for (uint32_t i = 0; i < size; i += kBlockSize, sector += kBlockSize / kSectorSize)
-        read(device, logs, sector, &buffer[i]);
+    for (uint32_t i = 0; i < size; i += block_size, sector += block_size / kSectorSize)
+        read(device, logs, sector, &buffer[i], block_size);
 
     return buffer;
 }
 
+}  // namespace
+
 Status cp_restoreCheckpoint(const std::string& blockDevice) {
     bool validating = true;
     std::string action = "Validating";
@@ -353,17 +353,19 @@ Status cp_restoreCheckpoint(const std::string& blockDevice) {
             PLOG(ERROR) << "Cannot open " << blockDevice;
             return Status::fromExceptionCode(errno, ("Cannot open " + blockDevice).c_str());
         }
-        auto buffer = read(device, logs, validating, 0, kBlockSize);
-        log_sector& ls = *reinterpret_cast<log_sector*>(&buffer[0]);
-        if (ls.magic != kMagic) {
+
+        log_sector original_ls;
+        device.read(reinterpret_cast<char*>(&original_ls), sizeof(original_ls));
+        if (original_ls.magic != kMagic) {
             LOG(ERROR) << "No magic";
             return Status::fromExceptionCode(EINVAL, "No magic");
         }
 
-        LOG(INFO) << action << " " << ls.sequence << " log sectors";
+        LOG(INFO) << action << " " << original_ls.sequence << " log sectors";
 
-        for (int sequence = ls.sequence; sequence >= 0 && status.isOk(); sequence--) {
-            auto buffer = read(device, logs, validating, 0, kBlockSize);
+        for (int sequence = original_ls.sequence; sequence >= 0 && status.isOk(); sequence--) {
+            auto buffer =
+                read(device, logs, validating, 0, original_ls.block_size, original_ls.block_size);
             log_sector& ls = *reinterpret_cast<log_sector*>(&buffer[0]);
             if (ls.magic != kMagic) {
                 LOG(ERROR) << "No magic!";
@@ -371,6 +373,12 @@ Status cp_restoreCheckpoint(const std::string& blockDevice) {
                 break;
             }
 
+            if (ls.block_size != original_ls.block_size) {
+                LOG(ERROR) << "Block size mismatch!";
+                status = Status::fromExceptionCode(EINVAL, "Block size mismatch");
+                break;
+            }
+
             if ((int)ls.sequence != sequence) {
                 LOG(ERROR) << "Expecting log sector " << sequence << " but got " << ls.sequence;
                 status = Status::fromExceptionCode(
@@ -385,10 +393,10 @@ Status cp_restoreCheckpoint(const std::string& blockDevice) {
             for (log_entry* le = &ls.entries[ls.count - 1]; le >= ls.entries; --le) {
                 LOG(INFO) << action << " " << le->size << " bytes from sector " << le->dest
                           << " to " << le->source << " with checksum " << std::hex << le->checksum;
-                auto buffer = read(device, logs, validating, le->dest, le->size);
-                uint32_t checksum = le->source / (kBlockSize / kSectorSize);
-                for (size_t i = 0; i < le->size; i += kBlockSize) {
-                    crc32(&buffer[i], kBlockSize, &checksum);
+                auto buffer = read(device, logs, validating, le->dest, le->size, ls.block_size);
+                uint32_t checksum = le->source / (ls.block_size / kSectorSize);
+                for (size_t i = 0; i < le->size; i += ls.block_size) {
+                    crc32(&buffer[i], ls.block_size, &checksum);
                 }
 
                 if (le->checksum && checksum != le->checksum) {
@@ -413,9 +421,10 @@ Status cp_restoreCheckpoint(const std::string& blockDevice) {
             }
 
             LOG(WARNING) << "Checkpoint validation failed - attempting to roll forward";
-            auto buffer = read(device, logs, false, ls.sector0, kBlockSize);
+            auto buffer = read(device, logs, false, original_ls.sector0, original_ls.block_size,
+                               original_ls.block_size);
             device.seekg(0);
-            device.write(&buffer[0], kBlockSize);
+            device.write(&buffer[0], original_ls.block_size);
             return Status::ok();
         }