diff --git a/src/main/java/net/sourceforge/tess4j/util/ImageIOHelper.java b/src/main/java/net/sourceforge/tess4j/util/ImageIOHelper.java
index 2eeb60ee..c096fd3f 100644
--- a/src/main/java/net/sourceforge/tess4j/util/ImageIOHelper.java
+++ b/src/main/java/net/sourceforge/tess4j/util/ImageIOHelper.java
@@ -23,6 +23,7 @@
 import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.io.IOException;
+import java.nio.Buffer;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 import java.util.ArrayList;
@@ -312,7 +313,7 @@ public static ByteBuffer convertImageData(BufferedImage bi) {
         ByteBuffer buf = ByteBuffer.allocateDirect(pixelData.length);
         buf.order(ByteOrder.nativeOrder());
         buf.put(pixelData);
-        buf.flip();
+        ((Buffer) buf).flip();
         return buf;
     }
 
diff --git a/src/main/resources/versionchanges.txt b/src/main/resources/versionchanges.txt
index 190e0991..c8b25932 100644
--- a/src/main/resources/versionchanges.txt
+++ b/src/main/resources/versionchanges.txt
@@ -163,4 +163,5 @@ Version 4.2.0 (11 August 2018)
 - Upgrade to Tesseract 4.0.0-beta.4 (fd49206)
 
 Version 4.2.1 (11 August 2018)
-- Recompile using JDK8 to avoid NoSuchMethodError: Method flip() does not exist in class java.nio.ByteBuffer
\ No newline at end of file
+- Recompile using JDK8 to avoid NoSuchMethodError: Method flip() does not exist in class java.nio.ByteBuffer
+- Use explicit cast for compatibility with covariant return type on JDK 9's ByteBuffer methods, e.g., flip()
\ No newline at end of file