diff --git a/actor-tests/src/test/scala/org/apache/pekko/util/LineNumbersConstantPoolSpec.scala b/actor-tests/src/test/scala/org/apache/pekko/util/LineNumbersConstantPoolSpec.scala
new file mode 100644
index 00000000000..40034fe5c58
--- /dev/null
+++ b/actor-tests/src/test/scala/org/apache/pekko/util/LineNumbersConstantPoolSpec.scala
@@ -0,0 +1,120 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.pekko.util
+
+import java.io.ByteArrayInputStream
+import java.io.InputStream
+import java.nio.ByteBuffer
+import java.nio.ByteOrder
+
+import org.apache.pekko
+import pekko.testkit.PekkoSpec
+
+/**
+ * Covers constant pool entry kinds that the class file format gained after Java 8:
+ * `CONSTANT_Dynamic` (tag 17, class file format 55.0) and `CONSTANT_Module` /
+ * `CONSTANT_Package` (tags 19 and 20, format 53.0).
+ *
+ * Neither scalac nor javac emits these for the code in this repository today, so the test
+ * takes a real class file and splices the entry into its constant pool. Entry sizes in the
+ * pool are tag dependent, so failing to recognise a tag makes every later entry unreadable --
+ * which is exactly the regression being guarded against.
+ */
+class LineNumbersConstantPoolSpec extends PekkoSpec {
+
+  private def classFileBytes(clazz: Class[?]): Array[Byte] = {
+    val resource = clazz.getName.replace('.', '/') + ".class"
+    val in = clazz.getClassLoader.getResourceAsStream(resource)
+    try {
+      val out = new java.io.ByteArrayOutputStream()
+      in.transferTo(out)
+      out.toByteArray
+    } finally in.close()
+  }
+
+  /** Offset of the first byte after the constant pool, and the pool's declared entry count. */
+  private def poolExtent(bytes: Array[Byte]): (Int, Int) = {
+    val count = ByteBuffer.wrap(bytes, 8, 2).order(ByteOrder.BIG_ENDIAN).getShort & 0xFFFF
+    var offset = 10
+    var index = 1
+    while (index < count) {
+      val tag = bytes(offset) & 0xFF
+      offset += 1
+      tag match {
+        case 1 => // Utf8: two length bytes then the bytes themselves
+          offset += 2 + (ByteBuffer.wrap(bytes, offset, 2).order(ByteOrder.BIG_ENDIAN).getShort & 0xFFFF)
+        case 5 | 6 => // Long, Double: take two pool slots
+          offset += 8
+          index += 1
+        case 7 | 8 | 16 | 19 | 20 => offset += 2
+        case 15                   => offset += 3
+        case _                    => offset += 4
+      }
+      index += 1
+    }
+    (offset, count)
+  }
+
+  /** Splices `entry` into the constant pool of `bytes` and bumps the pool count. */
+  private def withExtraPoolEntry(bytes: Array[Byte], entry: Array[Byte]): Array[Byte] = {
+    val (poolEnd, count) = poolExtent(bytes)
+    val result = new Array[Byte](bytes.length + entry.length)
+    System.arraycopy(bytes, 0, result, 0, poolEnd)
+    System.arraycopy(entry, 0, result, poolEnd, entry.length)
+    System.arraycopy(bytes, poolEnd, result, poolEnd + entry.length, bytes.length - poolEnd)
+    val bumped = count + 1
+    result(8) = ((bumped >> 8) & 0xFF).toByte
+    result(9) = (bumped & 0xFF).toByte
+    result
+  }
+
+  private def parse(bytes: Array[Byte]): LineNumbers.Result = {
+    val method = LineNumbers.getClass.getDeclaredMethod("getInfo", classOf[InputStream], classOf[Option[?]])
+    method.setAccessible(true)
+    method.invoke(LineNumbers, new ByteArrayInputStream(bytes), None).asInstanceOf[LineNumbers.Result]
+  }
+
+  private def twoByteEntry(tag: Int): Array[Byte] = Array(tag.toByte, 0, 1)
+  private def fourByteEntry(tag: Int): Array[Byte] = Array(tag.toByte, 0, 0, 0, 1)
+
+  "LineNumbers" must {
+
+    "read a class file whose constant pool it fully understands" in {
+      // baseline: the unmodified class parses, so any failure below is down to the new entry
+      parse(classFileBytes(classOf[LineNumbersConstantPoolSpec])) should not be a[LineNumbers.UnknownSourceFormat]
+    }
+
+    "read a constant pool containing a CONSTANT_Dynamic entry" in {
+      val spliced = withExtraPoolEntry(classFileBytes(classOf[LineNumbersConstantPoolSpec]), fourByteEntry(17))
+      parse(spliced) should not be a[LineNumbers.UnknownSourceFormat]
+    }
+
+    "read a constant pool containing CONSTANT_Module and CONSTANT_Package entries" in {
+      val base = classFileBytes(classOf[LineNumbersConstantPoolSpec])
+      parse(withExtraPoolEntry(base, twoByteEntry(19))) should not be a[LineNumbers.UnknownSourceFormat]
+      parse(withExtraPoolEntry(base, twoByteEntry(20))) should not be a[LineNumbers.UnknownSourceFormat]
+    }
+
+    "report an unparseable class file instead of throwing" in {
+      // an unrecognised tag leaves the rest of the pool unreadable; the parser must still
+      // return a result rather than propagating an exception
+      val spliced = withExtraPoolEntry(classFileBytes(classOf[LineNumbersConstantPoolSpec]), fourByteEntry(99))
+      parse(spliced) shouldBe a[LineNumbers.UnknownSourceFormat]
+    }
+  }
+}
diff --git a/actor/src/main/scala/org/apache/pekko/util/LineNumbers.scala b/actor/src/main/scala/org/apache/pekko/util/LineNumbers.scala
index 6c82e79f2c0..f4d0594c2a1 100644
--- a/actor/src/main/scala/org/apache/pekko/util/LineNumbers.scala
+++ b/actor/src/main/scala/org/apache/pekko/util/LineNumbers.scala
@@ -23,12 +23,11 @@ import org.apache.pekko.annotation.DoNotInherit
 
 /**
  * This is a minimized byte-code parser that concentrates exclusively on line
- * numbers and source file extraction. It works for all normal classes up to
- * format 52:0 (JDK8), and it also works for Lambdas that are Serializable. The
- * latter restriction is due to the fact that the proxy object generated by
- * LambdaMetafactory otherwise contains no information about which method backs
- * this particular lambda (and there might be multiple defined within a single
- * class).
+ * numbers and source file extraction. It works for normal classes, and it also
+ * works for Lambdas that are Serializable. The latter restriction is due to the
+ * fact that the proxy object generated by LambdaMetafactory otherwise contains
+ * no information about which method backs this particular lambda (and there
+ * might be multiple defined within a single class).
  */
 object LineNumbers {
 
@@ -162,9 +161,23 @@ object LineNumbers {
         case 16 => // MethodType
           skip(d, 2)
           nextIdx += 1
+        case 17 => // Dynamic (JVMS 4.4.13, class file format 55.0 / Java 11)
+          skip(d, 4) // two shorts
+          nextIdx += 1
         case 18 => // InvokeDynamic
           skip(d, 4) // two shorts
           nextIdx += 1
+        case 19 => // Module (JVMS 4.4.11, class file format 53.0 / Java 9)
+          skip(d, 2)
+          nextIdx += 1
+        case 20 => // Package (JVMS 4.4.12, class file format 53.0 / Java 9)
+          skip(d, 2)
+          nextIdx += 1
+        case other =>
+          // An unknown tag means the rest of the pool cannot be located, since entry sizes are
+          // tag dependent. Fail with a description rather than a MatchError; getInfo turns this
+          // into an UnknownSourceFormat result.
+          throw new UnsupportedOperationException(s"unknown constant pool tag [$other]")
       }
 
   }