diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/util/IOUtil.java b/pmd-core/src/main/java/net/sourceforge/pmd/util/IOUtil.java
index 791561bc7a..881bc7efa2 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/util/IOUtil.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/util/IOUtil.java
@@ -325,7 +325,7 @@ public final class IOUtil {
                     charBuffer.flip();
                     encoder.encode(charBuffer, byteBuffer, eof);
                     byteBuffer.flip();
-                    charBuffer.flip();
+                    charBuffer.compact();
                 }
 
                 if (byteBuffer.hasRemaining()) {
diff --git a/pmd-core/src/test/java/net/sourceforge/pmd/util/IOUtilTest.java b/pmd-core/src/test/java/net/sourceforge/pmd/util/IOUtilTest.java
index 7b21230fb6..b577de8f11 100644
--- a/pmd-core/src/test/java/net/sourceforge/pmd/util/IOUtilTest.java
+++ b/pmd-core/src/test/java/net/sourceforge/pmd/util/IOUtilTest.java
@@ -193,6 +193,21 @@ public class IOUtilTest {
         }
     }
 
+    @Test
+    public void testInputStreamFromReader2() throws IOException {
+        int size = 8192 + 8192 + 10;
+        char[] data = new char[size];
+        for (int i = 0; i < size; i++) {
+            data[i] = 'A';
+        }
+        data[8192] = 'ä'; // block size border - in UTF-8 these are two bytes. Decoding needs to take the bytes
+        // from previous block and new block
+        try (InputStream inputStream = IOUtil.fromReader(new StringReader(new String(data)))) {
+            byte[] bytes = IOUtil.toByteArray(inputStream);
+            Assert.assertEquals(new String(data), new String(bytes, StandardCharsets.UTF_8));
+        }
+    }
+
     @Test
     public void testCopyStream() throws IOException {
         int size = 8192 + 8192 + 10;