diff --git a/src/org/geometerplus/android/fbreader/libraryService/BookCollectionShadow.java b/src/org/geometerplus/android/fbreader/libraryService/BookCollectionShadow.java
index 624005972..7df00b873 100644
--- a/src/org/geometerplus/android/fbreader/libraryService/BookCollectionShadow.java
+++ b/src/org/geometerplus/android/fbreader/libraryService/BookCollectionShadow.java
@@ -322,6 +322,17 @@ public class BookCollectionShadow extends AbstractBookCollection implements Serv
 		return Collections.emptyList();
 	}
 
+	public String getHash(Book book) {
+		if (myInterface == null) {
+			return null;
+		}
+		try {
+			return myInterface.getHash(SerializerUtil.serialize(book));
+		} catch (RemoteException e) {
+			return null;
+		}
+	}
+
 	public synchronized ZLTextPosition getStoredPosition(long bookId) {
 		if (myInterface == null) {
 			return null;
diff --git a/src/org/geometerplus/android/fbreader/libraryService/LibraryInterface.aidl b/src/org/geometerplus/android/fbreader/libraryService/LibraryInterface.aidl
index b3b99fb78..c8907fe23 100644
--- a/src/org/geometerplus/android/fbreader/libraryService/LibraryInterface.aidl
+++ b/src/org/geometerplus/android/fbreader/libraryService/LibraryInterface.aidl
@@ -52,4 +52,6 @@ interface LibraryInterface {
 	void saveHighlightingStyle(in String style);
 
 	void rescan(in String path);
+
+	String getHash(in String book);
 }
diff --git a/src/org/geometerplus/android/fbreader/libraryService/LibraryService.java b/src/org/geometerplus/android/fbreader/libraryService/LibraryService.java
index fb3878699..b2e8052c4 100644
--- a/src/org/geometerplus/android/fbreader/libraryService/LibraryService.java
+++ b/src/org/geometerplus/android/fbreader/libraryService/LibraryService.java
@@ -320,6 +320,10 @@ public class LibraryService extends Service {
 		public void rescan(String path) {
 			myCollection.rescan(path);
 		}
+
+		public String getHash(String book) {
+			return myCollection.getHash(SerializerUtil.deserializeBook(book));
+		}
 	}
 
 	private volatile LibraryImplementation myLibrary;
diff --git a/src/org/geometerplus/android/fbreader/libraryService/SQLiteBooksDatabase.java b/src/org/geometerplus/android/fbreader/libraryService/SQLiteBooksDatabase.java
index 8a9d4939f..7380ce6aa 100644
--- a/src/org/geometerplus/android/fbreader/libraryService/SQLiteBooksDatabase.java
+++ b/src/org/geometerplus/android/fbreader/libraryService/SQLiteBooksDatabase.java
@@ -23,8 +23,7 @@ import java.util.*;
 import java.math.BigDecimal;
 
 import android.content.Context;
-import android.database.sqlite.SQLiteDatabase;
-import android.database.sqlite.SQLiteStatement;
+import android.database.sqlite.*;
 import android.database.SQLException;
 import android.database.Cursor;
 
@@ -975,14 +974,29 @@ final class SQLiteBooksDatabase extends BooksDatabase {
 		return progress;
 	}
 
-	//@Override
-	String getHash(long bookId, long lastModified) {
+	@Override
+	protected String getHash(long bookId, long lastModified) {
 		final SQLiteStatement statement = get(
-			"SELECT hash FROM BookHash WHERE bookId=? AND timestamp>?"
+			"SELECT hash FROM BookHash WHERE book_id=? AND timestamp>?"
 		);
 		statement.bindLong(1, bookId);
 		statement.bindLong(2, lastModified);
-		return statement.simpleQueryForString();
+		try {
+			return statement.simpleQueryForString();
+		} catch (SQLiteDoneException e) {
+			return null;
+		}
+	}
+
+	@Override
+	protected void setHash(long bookId, String hash) {
+		final SQLiteStatement statement = get(
+			"INSERT OR REPLACE INTO BookHash (book_id,timestamp,hash) VALUES (?,?,?)"
+		);
+		statement.bindLong(1, bookId);
+		statement.bindLong(2, System.currentTimeMillis());
+		statement.bindString(3, hash);
+		statement.executeInsert();
 	}
 
 	@Override
diff --git a/src/org/geometerplus/android/fbreader/synchroniser/SynchroniserService.java b/src/org/geometerplus/android/fbreader/synchroniser/SynchroniserService.java
index 59b6e2f44..1e18f80fe 100644
--- a/src/org/geometerplus/android/fbreader/synchroniser/SynchroniserService.java
+++ b/src/org/geometerplus/android/fbreader/synchroniser/SynchroniserService.java
@@ -97,7 +97,7 @@ public class SynchroniserService extends Service implements IBookCollection.List
 							}
 							myProcessed.add(book);
 							System.err.println("Processing " + book.getTitle() + " [" + book.File.getPath() + "]");
-							uploadBookToServer(book.File.getPhysicalFile());
+							uploadBookToServer(book);
 						}
 					} finally {
 						System.err.println("BYE-BYE THREAD");
@@ -164,19 +164,23 @@ public class SynchroniserService extends Service implements IBookCollection.List
 		}
 	}
 
-	private void uploadBookToServer(ZLPhysicalFile file) {
-		final UID uid = BookUtil.createUid(file, "SHA-1");
-		if (uid == null) {
-			System.err.println("Failed: SHA-1 checksum not computed");
+	private void uploadBookToServer(Book book) {
+		final ZLPhysicalFile file = book.File.getPhysicalFile();
+		if (file == null) {
 			return;
 		}
-		if (myHashesFromServer.contains(uid.Id.toLowerCase())) {
+		final String hash = myCollection.getHash(book);
+		if (hash == null) {
+			System.err.println("Failed: checksum not computed");
+			return;
+		}
+		if (myHashesFromServer.contains(hash)) {
 			System.err.println("HASH ALREADY IN THE TABLE");
 			return;
 		}
 		final Map<String,Object> result = new HashMap<String,Object>();
 		final PostRequest verificationRequest =
-			new PostRequest("books.by.hash", Collections.singletonMap("sha1", uid.Id)) {
+			new PostRequest("books.by.hash", Collections.singletonMap("sha1", hash)) {
 				@Override
 				public void processResponse(Object response) {
 					result.put("result", response);
diff --git a/src/org/geometerplus/fbreader/book/BookCollection.java b/src/org/geometerplus/fbreader/book/BookCollection.java
index c279748e0..f1dd14e8a 100644
--- a/src/org/geometerplus/fbreader/book/BookCollection.java
+++ b/src/org/geometerplus/fbreader/book/BookCollection.java
@@ -711,4 +711,22 @@ public class BookCollection extends AbstractBookCollection {
 		myDatabase.saveStyle(style);
 		fireBookEvent(BookEvent.BookmarkStyleChanged, null);
 	}
+
+	public String getHash(Book book) {
+		final ZLPhysicalFile file = book.File.getPhysicalFile();
+		if (file == null) {
+			return null;
+		}
+		String hash = myDatabase.getHash(book.getId(), file.javaFile().lastModified());
+		System.err.println("HASH FOR " + book + " FROM DB = " + hash);
+		if (hash == null) {
+			final UID uid = BookUtil.createUid(file, "SHA-1");
+			if (uid == null) {
+				return null;
+			}
+			hash = uid.Id.toLowerCase();
+			myDatabase.setHash(book.getId(), hash);
+		}
+		return hash;
+	}
 }
diff --git a/src/org/geometerplus/fbreader/book/BooksDatabase.java b/src/org/geometerplus/fbreader/book/BooksDatabase.java
index 2d9b1a3ec..eadcde2b3 100644
--- a/src/org/geometerplus/fbreader/book/BooksDatabase.java
+++ b/src/org/geometerplus/fbreader/book/BooksDatabase.java
@@ -126,4 +126,7 @@ public abstract class BooksDatabase {
 
 	protected abstract Collection<String> loadVisitedHyperlinks(long bookId);
 	protected abstract void addVisitedHyperlink(long bookId, String hyperlinkId);
+
+	protected abstract String getHash(long bookId, long lastModified);
+	protected abstract void setHash(long bookId, String hash);
 }
diff --git a/src/org/geometerplus/fbreader/book/IBookCollection.java b/src/org/geometerplus/fbreader/book/IBookCollection.java
index 810b85bfb..a1bcb4f96 100644
--- a/src/org/geometerplus/fbreader/book/IBookCollection.java
+++ b/src/org/geometerplus/fbreader/book/IBookCollection.java
@@ -73,6 +73,8 @@ public interface IBookCollection {
 	boolean saveBook(Book book);
 	void removeBook(Book book, boolean deleteFromDisk);
 
+	String getHash(Book book);
+
 	ZLTextPosition getStoredPosition(long bookId);
 	void storePosition(long bookId, ZLTextPosition position);