diff --git a/src/org/geometerplus/fbreader/book/BookCollection.java b/src/org/geometerplus/fbreader/book/BookCollection.java
index 16ceb6388..2f42255b8 100644
--- a/src/org/geometerplus/fbreader/book/BookCollection.java
+++ b/src/org/geometerplus/fbreader/book/BookCollection.java
@@ -64,6 +64,9 @@ public class BookCollection extends AbstractBookCollection {
 		if (plugin == null) {
 			return null;
 		}
+		if (!plugin.type().Builtin && bookFile != bookFile.getPhysicalFile()) {
+			return null;
+		}
 		try {
 			bookFile = plugin.realBookFile(bookFile);
 		} catch (BookReadingException e) {
diff --git a/src/org/geometerplus/fbreader/formats/FormatPlugin.java b/src/org/geometerplus/fbreader/formats/FormatPlugin.java
index 994497fd2..48d8698e5 100644
--- a/src/org/geometerplus/fbreader/formats/FormatPlugin.java
+++ b/src/org/geometerplus/fbreader/formats/FormatPlugin.java
@@ -50,12 +50,18 @@ public abstract class FormatPlugin {
 	public abstract String readAnnotation(ZLFile file);
 
 	public enum Type {
-		ANY,
-		JAVA,
-		NATIVE,
-		PLUGIN,
-		EXTERNAL,
-		NONE
+		ANY(false),
+		JAVA(true),
+		NATIVE(true),
+		PLUGIN(false),
+		EXTERNAL(false),
+		NONE(false);
+
+		public final boolean Builtin;
+
+		Type(boolean builtin) {
+			Builtin = builtin;
+		}
 	};
 	public abstract Type type();