diff --git a/taglib/matroska/ebml/ebmlelement.cpp b/taglib/matroska/ebml/ebmlelement.cpp
index bde73ff6..27b43240 100644
--- a/taglib/matroska/ebml/ebmlelement.cpp
+++ b/taglib/matroska/ebml/ebmlelement.cpp
@@ -52,12 +52,14 @@ std::unique_ptr<EBML::Element> EBML::Element::factory(File &file, offset_t maxOf
   }
 
   // Get the size length and data length
-  const auto &[sizeLength, dataSize] = readVINT(file);
+  auto [sizeLength, dataSize] = readVINT(file);
   if(!sizeLength)
     return nullptr;
 
   if(const offset_t currentOffset = file.tell();
-     static_cast<offset_t>(dataSize) > maxOffset - currentOffset) {
+     isUnknownSize(sizeLength, dataSize)) {
+    dataSize = maxOffset - currentOffset;
+  } else if(static_cast<offset_t>(dataSize) > maxOffset - currentOffset) {
     debug(Utils::formatString("EBML: datasize too great: %lu > (%lld - %lld)",
       dataSize, maxOffset, currentOffset));
     return nullptr;
diff --git a/taglib/matroska/ebml/ebmlutils.h b/taglib/matroska/ebml/ebmlutils.h
index 4038e5b0..f35228dd 100644
--- a/taglib/matroska/ebml/ebmlutils.h
+++ b/taglib/matroska/ebml/ebmlutils.h
@@ -71,6 +71,18 @@ namespace TagLib {
         return 3;
       return 4;
     }
+
+    // See https://datatracker.ietf.org/doc/rfc8794/ section 6.2
+    constexpr bool isUnknownSize(unsigned int sizeLength, uint64_t dataSize)
+    {
+      if(sizeLength == 0 || sizeLength > 8) {
+        return false;
+      }
+
+      const unsigned int numDataBits = sizeLength * 8 - sizeLength;
+      const uint64_t mask = (1ULL << numDataBits) - 1;
+      return (dataSize & mask) == mask;
+    }
   }
 }
 
diff --git a/tests/test_matroska.cpp b/tests/test_matroska.cpp
index 2e2746e7..5ec0e79e 100644
--- a/tests/test_matroska.cpp
+++ b/tests/test_matroska.cpp
@@ -160,6 +160,7 @@ class TestMatroska : public CppUnit::TestFixture
   CPPUNIT_TEST(testSaveTypesBeforeCues);
   CPPUNIT_TEST(testSaveTypesNoTrailingVoid);
   CPPUNIT_TEST(testSaveTypesReclaimVoid);
+  CPPUNIT_TEST(testUnknownSizeSegment);
   CPPUNIT_TEST_SUITE_END();
 
 public:
@@ -1777,6 +1778,56 @@ public:
     }
   }
 
+  void testUnknownSizeSegment()
+  {
+    ScopedFileCopy copy("no-tags", ".mka");
+    string newname = copy.fileName();
+
+    // Modify the copied file (/tmp/taglib-test.mka on Linux) to have elements
+    // with unknown size length.
+    {
+      PlainFile file(newname.c_str());
+      ByteVector fileData = file.readAll();
+      CPPUNIT_ASSERT_EQUAL(12390U, fileData.size());
+      // Size of Segment
+      for(int i = 0x2d; i <= 0x33; ++i) {
+        fileData[i] = '\xff';
+      }
+      // Size of Cluster
+      for(int i = 0x2d; i <= 0x33; ++i) {
+        fileData[i] = '\xff';
+      }
+      fileData[0x1482] = '\x7f';
+      fileData[0x1483] = '\xff';
+      file.seek(0);
+      file.writeBlock(fileData);
+    }
+    {
+      Matroska::File f(newname.c_str(), true, AudioProperties::Accurate);
+      CPPUNIT_ASSERT(f.isValid());
+      CPPUNIT_ASSERT(f.audioProperties());
+      CPPUNIT_ASSERT_EQUAL(444, f.audioProperties()->lengthInMilliseconds());
+      CPPUNIT_ASSERT_EQUAL(223, f.audioProperties()->bitrate());
+      CPPUNIT_ASSERT_EQUAL(2, f.audioProperties()->channels());
+      CPPUNIT_ASSERT_EQUAL(44100, f.audioProperties()->sampleRate());
+      CPPUNIT_ASSERT_EQUAL(String("matroska"), f.audioProperties()->docType());
+      CPPUNIT_ASSERT_EQUAL(4, f.audioProperties()->docTypeVersion());
+      CPPUNIT_ASSERT_EQUAL(String("A_MPEG/L3"), f.audioProperties()->codecName());
+      CPPUNIT_ASSERT_EQUAL(String(""), f.audioProperties()->title());
+      CPPUNIT_ASSERT(!f.tag(false));
+      CPPUNIT_ASSERT(!f.attachments(false));
+      auto tag = f.tag(true);
+      CPPUNIT_ASSERT(tag->isEmpty());
+      tag->setTitle("Unknown size");
+      CPPUNIT_ASSERT(f.save());
+    }
+    {
+      Matroska::File f(newname.c_str(), true, AudioProperties::Accurate);
+      CPPUNIT_ASSERT(f.isValid());
+      CPPUNIT_ASSERT(f.tag(false));
+      CPPUNIT_ASSERT_EQUAL(String("Unknown size"), f.tag()->title());
+    }
+  }
 };
 
 CPPUNIT_TEST_SUITE_REGISTRATION(TestMatroska);