diff --git a/jni/NativeFormats/JavaNativeFormatPlugin.cpp b/jni/NativeFormats/JavaNativeFormatPlugin.cpp
index 24643f947..a53f39da8 100644
--- a/jni/NativeFormats/JavaNativeFormatPlugin.cpp
+++ b/jni/NativeFormats/JavaNativeFormatPlugin.cpp
@@ -287,6 +287,6 @@ JNIEXPORT jboolean JNICALL Java_org_geometerplus_fbreader_formats_NativeFormatPl
 }
 
 extern "C"
-JNIEXPORT jobject JNICALL Java_org_geometerplus_fbreader_formats_NativeFormatPlugin_readCoverInternal(JNIEnv* env, jobject thiz, jobject file) {
-	return 0;
+JNIEXPORT void JNICALL Java_org_geometerplus_fbreader_formats_NativeFormatPlugin_readCoverInternal(JNIEnv* env, jobject thiz, jobject file, jobjectArray box) {
+	// TODO: implement
 }
diff --git a/src/org/geometerplus/fbreader/formats/NativeFormatPlugin.java b/src/org/geometerplus/fbreader/formats/NativeFormatPlugin.java
index 12ed02b5e..0f3a106ae 100644
--- a/src/org/geometerplus/fbreader/formats/NativeFormatPlugin.java
+++ b/src/org/geometerplus/fbreader/formats/NativeFormatPlugin.java
@@ -29,8 +29,6 @@ import org.geometerplus.fbreader.bookmodel.BookReadingException;
 import org.geometerplus.fbreader.library.Book;
 
 public class NativeFormatPlugin extends FormatPlugin {
-	private static Object ourCoversLock = new Object();
-
 	// No free method because all plugins' instances are freed by 
 	//   PluginCollection::deleteInstance method (C++)
 
@@ -74,15 +72,14 @@ public class NativeFormatPlugin extends FormatPlugin {
 
 			@Override
 			public ZLSingleImage getRealImage() {
-				// Synchronized block is needed because we use temporary storage files
-				synchronized (ourCoversLock) {
-					return (ZLSingleImage)readCoverInternal(file);
-				}
+				final ZLImage[] box = new ZLImage[1];
+				readCoverInternal(file, box);
+				return (ZLSingleImage)box[0];
 			}
 		};
 	}
 
-	protected native ZLImage readCoverInternal(ZLFile file);
+	protected native void readCoverInternal(ZLFile file, ZLImage[] box);
 
 	/*
 	public static ZLImage createImage(String mimeType, String fileName, int offset, int length) {