diff --git a/fbreader/app/src/main/java/org/amse/ys/zip/MyBufferedInputStream.java b/fbreader/app/src/main/java/org/amse/ys/zip/MyBufferedInputStream.java
index a29cc9fa4..8461d8a32 100644
--- a/fbreader/app/src/main/java/org/amse/ys/zip/MyBufferedInputStream.java
+++ b/fbreader/app/src/main/java/org/amse/ys/zip/MyBufferedInputStream.java
@@ -89,12 +89,43 @@ final class MyBufferedInputStream extends InputStream {
 		return (fourthByte << 24) + (thirdByte << 16) + (secondByte << 8) + firstByte;
 	}
 
-	String readString(int stringLength) throws IOException {
-		char[] array = new char[stringLength];
-		for (int i = 0; i < stringLength; i++) {
-			array[i] = (char)read();
+	private static final boolean isUtf8String(byte[] array) {
+		int nonLeadingCharsCounter = 0;
+		for (byte b : array) {
+			if (nonLeadingCharsCounter == 0) {
+				if ((b & 0x80) != 0) {
+					if ((b & 0xE0) == 0xC0) {
+						nonLeadingCharsCounter = 1;
+					} else if ((b & 0xF0) == 0xE0) {
+						nonLeadingCharsCounter = 2;
+					} else if ((b & 0xF8) == 0xF0) {
+						nonLeadingCharsCounter = 3;
+					} else {
+						return false;
+					}
+				}
+			} else {
+				if ((b & 0xC0) != 0x80) {
+					return false;
+				}
+				--nonLeadingCharsCounter;
+			}
 		}
-		return new String(array);
+		return nonLeadingCharsCounter == 0;
+	}
+
+	String readString(int stringLength) throws IOException {
+		final byte[] array = new byte[stringLength];
+		read(array);
+		if (isUtf8String(array)) {
+			return new String(array, "utf-8");
+		}
+
+		final char[] chars = new char[stringLength];
+		for (int i = 0; i < stringLength; i++) {
+			chars[i] = (char)(array[i] & 0xFF);
+		}
+		return new String(chars);
 	}
 
 	@Override
diff --git a/jni/NativeFormats/util/AndroidUtil.cpp b/jni/NativeFormats/util/AndroidUtil.cpp
index c91d2e7c0..712b46e1f 100644
--- a/jni/NativeFormats/util/AndroidUtil.cpp
+++ b/jni/NativeFormats/util/AndroidUtil.cpp
@@ -20,6 +20,7 @@
 #include <ZLFile.h>
 #include <FileEncryptionInfo.h>
 #include <ZLFileImage.h>
+#include <ZLUnicodeUtil.h>
 
 #include "AndroidUtil.h"
 #include "JniEnvelope.h"
@@ -288,13 +289,13 @@ jstring AndroidUtil::createJavaString(JNIEnv* env, const std::string &str) {
 }
 
 std::string AndroidUtil::convertNonUtfString(const std::string &str) {
-	const int len = str.length();
-	if (len == 0) {
+	if (ZLUnicodeUtil::isUtf8String(str)) {
 		return str;
 	}
 
 	JNIEnv *env = getEnv();
 
+	const int len = str.length();
 	jchar *chars = new jchar[len];
 	for (int i = 0; i < len; ++i) {
 		chars[i] = (unsigned char)str[i];