diff --git a/api/src/main/java/jakarta/xml/bind/DatatypeConverterImpl.java b/api/src/main/java/jakarta/xml/bind/DatatypeConverterImpl.java
index d8d61c2..0f0e378 100644
--- a/api/src/main/java/jakarta/xml/bind/DatatypeConverterImpl.java
+++ b/api/src/main/java/jakarta/xml/bind/DatatypeConverterImpl.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2007, 2021 Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2007, 2023 Oracle and/or its affiliates. All rights reserved.
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Distribution License v. 1.0, which is available at
@@ -706,6 +706,9 @@ private static int guessLength(String text) {
      */
     public static byte[] _parseBase64Binary(String text) {
         final int buflen = guessLength(text);
+        if (buflen < 3) {
+            throw new IllegalArgumentException("base64 text invalid.");
+        }
         final byte[] out = new byte[buflen];
         int o = 0;
 
@@ -725,6 +728,7 @@ public static byte[] _parseBase64Binary(String text) {
             }
 
             if (q == 4) {
+
                 // quadruplet is now filled.
                 out[o++] = (byte) ((quadruplet[0] << 2) | (quadruplet[1] >> 4));
                 if (quadruplet[2] != PADDING) {
diff --git a/api/src/test/java/org/eclipse/jaxb/api/DatatypeConverterTest.java b/api/src/test/java/org/eclipse/jaxb/api/DatatypeConverterTest.java
index 4fbf1c0..bfbe75e 100644
--- a/api/src/test/java/org/eclipse/jaxb/api/DatatypeConverterTest.java
+++ b/api/src/test/java/org/eclipse/jaxb/api/DatatypeConverterTest.java
@@ -55,4 +55,13 @@ public void testParseBoolean() {
         Assert.assertEquals(true, DatatypeConverter.parseBoolean("true "));
         Assert.assertEquals(true, DatatypeConverter.parseBoolean(" true "));
     }
+
+    @Test
+    public void testBase64() {
+        Assert.assertThrows(IllegalArgumentException.class, () -> DatatypeConverter.parseBase64Binary("Qxx=="));
+        Assert.assertNotEquals("Hello, world!", new String(DatatypeConverter.parseBase64Binary("SGVsbG8sIJdvcmxkIQ==")));
+
+        Assert.assertEquals("Hello, world!", new String(DatatypeConverter.parseBase64Binary("SGVsbG8sIHdvcmxkIQ==")));
+    }
+
 }