diff --git a/DBCD.IO/Readers/WDC4Reader.cs b/DBCD.IO/Readers/WDC4Reader.cs
index e440b6e..489f81a 100644
--- a/DBCD.IO/Readers/WDC4Reader.cs
+++ b/DBCD.IO/Readers/WDC4Reader.cs
@@ -283,12 +283,8 @@ public WDC4Reader(Stream stream)
                 int palletDataSize = reader.ReadInt32(); // in bytes, sizeof(DBC2PalletValue) == 4
                 int sectionsCount = reader.ReadInt32();
 
-                if (sectionsCount == 0 || RecordsCount == 0)
-                    return;
-
-                var sections = reader.ReadArray<SectionHeaderWDC4>(sectionsCount);
+                var sections = (sectionsCount == 0) ? new List<SectionHeaderWDC4>() : reader.ReadArray<SectionHeaderWDC4>(sectionsCount).ToList();
                 this.m_sections = sections.OfType<IEncryptableDatabaseSection>().ToList();
-                this.m_encryptedIDs = new Dictionary<ulong, int[]>();
 
                 // field meta data
                 Meta = reader.ReadArray<FieldMetaData>(FieldsCount);
@@ -296,6 +292,11 @@ public WDC4Reader(Stream stream)
                 // column meta data
                 ColumnMeta = reader.ReadArray<ColumnMetaData>(FieldsCount);
 
+                if (sectionsCount == 0 || RecordsCount == 0)
+                    return;
+
+                this.m_encryptedIDs = new Dictionary<ulong, int[]>();
+
                 // pallet data
                 PalletData = new Value32[ColumnMeta.Length][];
                 for (int i = 0; i < ColumnMeta.Length; i++)
diff --git a/DBCD.IO/Readers/WDC5Reader.cs b/DBCD.IO/Readers/WDC5Reader.cs
index 3199e14..d194ecc 100644
--- a/DBCD.IO/Readers/WDC5Reader.cs
+++ b/DBCD.IO/Readers/WDC5Reader.cs
@@ -287,12 +287,8 @@ public WDC5Reader(Stream stream)
                 int palletDataSize = reader.ReadInt32(); // in bytes, sizeof(DBC2PalletValue) == 4
                 int sectionsCount = reader.ReadInt32();
 
-                if (sectionsCount == 0 || RecordsCount == 0)
-                    return;
-
-                var sections = reader.ReadArray<SectionHeaderWDC4>(sectionsCount);
+                var sections = (sectionsCount == 0) ? new List<SectionHeaderWDC5>() : reader.ReadArray<SectionHeaderWDC5>(sectionsCount).ToList();
                 this.m_sections = sections.OfType<IEncryptableDatabaseSection>().ToList();
-                this.m_encryptedIDs = new Dictionary<ulong, int[]>();
 
                 // field meta data
                 Meta = reader.ReadArray<FieldMetaData>(FieldsCount);
@@ -300,6 +296,11 @@ public WDC5Reader(Stream stream)
                 // column meta data
                 ColumnMeta = reader.ReadArray<ColumnMetaData>(FieldsCount);
 
+                if(sectionsCount == 0 || RecordsCount == 0)
+                    return;
+
+                this.m_encryptedIDs = new Dictionary<ulong, int[]>();
+
                 // pallet data
                 PalletData = new Value32[ColumnMeta.Length][];
                 for (int i = 0; i < ColumnMeta.Length; i++)
diff --git a/DBCD.IO/Writers/WDC4Writer.cs b/DBCD.IO/Writers/WDC4Writer.cs
index 0afe6e6..01c96f9 100644
--- a/DBCD.IO/Writers/WDC4Writer.cs
+++ b/DBCD.IO/Writers/WDC4Writer.cs
@@ -339,7 +339,7 @@ public WDC4Writer(WDC4Reader reader, IDictionary<int, T> storage, Stream stream)
                 writer.Write(fileOffset);                       // FileOffset
                 writer.Write(RecordsCount);                     // NumRecords
                 writer.Write(StringTableSize);
-                writer.Write(0);                                // OffsetRecordsEndOffset
+                writer.Write(0);                                // OffsetRecordsEndOffset, this is set after writing the records for sparse tables
                 writer.Write(Flags.HasFlagExt(DB2Flags.Index) ? RecordsCount * 4 : 0);  // IndexDataSize
                 writer.Write(referenceDataSize);                // ParentLookupDataSize
                 writer.Write(Flags.HasFlagExt(DB2Flags.Sparse) ? RecordsCount : 0); // OffsetMapIDCount
@@ -404,7 +404,7 @@ public WDC4Writer(WDC4Reader reader, IDictionary<int, T> storage, Stream stream)
                 if (Flags.HasFlagExt(DB2Flags.Sparse))
                 {
                     long oldPos = writer.BaseStream.Position;
-                    writer.BaseStream.Position = 92;
+                    writer.BaseStream.Position = HeaderSize + 20;
                     writer.Write((uint)oldPos);
                     writer.BaseStream.Position = oldPos;
                 }
@@ -424,6 +424,10 @@ public WDC4Writer(WDC4Reader reader, IDictionary<int, T> storage, Stream stream)
                 if (Flags.HasFlagExt(DB2Flags.Sparse))
                     writer.WriteArray(SparseEntries.Values.ToArray());
 
+                // sparse data ids (if flag 0x2 is set)
+                if (Flags.HasFlagExt(DB2Flags.Sparse) && Flags.HasFlag(DB2Flags.SecondaryKey))
+                    writer.WriteArray(SparseEntries.Keys.ToArray());
+
                 // reference data
                 if (ReferenceData.Count > 0)
                 {
@@ -434,12 +438,15 @@ public WDC4Writer(WDC4Reader reader, IDictionary<int, T> storage, Stream stream)
                     for (int i = 0; i < ReferenceData.Count; i++)
                     {
                         writer.Write(ReferenceData[i]);
-                        writer.Write(i);
+                        if (Flags.HasFlag(DB2Flags.SecondaryKey))
+                            writer.Write(SparseEntries.Keys.ElementAt(i));
+                        else
+                            writer.Write(i);
                     }
                 }
 
-                // sparse data ids
-                if (Flags.HasFlagExt(DB2Flags.Sparse))
+                // sparse data ids (if flag 0x2 is not set)
+                if (Flags.HasFlagExt(DB2Flags.Sparse) && !Flags.HasFlag(DB2Flags.SecondaryKey))
                     writer.WriteArray(SparseEntries.Keys.ToArray());
             }
         }
diff --git a/DBCD.IO/Writers/WDC5Writer.cs b/DBCD.IO/Writers/WDC5Writer.cs
index fe88421..a18e249 100644
--- a/DBCD.IO/Writers/WDC5Writer.cs
+++ b/DBCD.IO/Writers/WDC5Writer.cs
@@ -276,7 +276,7 @@ private static void WriteFieldValueArray<TType>(BitWriter r, FieldMetaData field
 
     class WDC5Writer<T> : BaseWriter<T> where T : class
     {
-        private const int HeaderSize = 200;
+        private const int HeaderSize = 204;
         private const uint WDC5FmtSig = 0x35434457; // WDC5
 
         public WDC5Writer(WDC5Reader reader, IDictionary<int, T> storage, Stream stream) : base(reader)
@@ -308,9 +308,8 @@ public WDC5Writer(WDC5Reader reader, IDictionary<int, T> storage, Stream stream)
                 int maxIndex = storage.Keys.MaxOrDefault();
 
                 writer.Write(WDC5FmtSig);
-                writer.Write((uint)5); // numaric version
+                writer.Write((uint)5); // numeric version
                 writer.Write(Encoding.ASCII.GetBytes(staticVersionString.PadRight(128, '\0')));
-
                 writer.Write(RecordsCount);
                 writer.Write(FieldsCount);
                 writer.Write(RecordSize);
@@ -345,7 +344,7 @@ public WDC5Writer(WDC5Reader reader, IDictionary<int, T> storage, Stream stream)
                 writer.Write(fileOffset);                       // FileOffset
                 writer.Write(RecordsCount);                     // NumRecords
                 writer.Write(StringTableSize);
-                writer.Write(0);                                // OffsetRecordsEndOffset
+                writer.Write(0);                                // OffsetRecordsEndOffset, this is set after writing the records for sparse tables
                 writer.Write(Flags.HasFlagExt(DB2Flags.Index) ? RecordsCount * 4 : 0);  // IndexDataSize
                 writer.Write(referenceDataSize);                // ParentLookupDataSize
                 writer.Write(Flags.HasFlagExt(DB2Flags.Sparse) ? RecordsCount : 0); // OffsetMapIDCount
@@ -410,7 +409,7 @@ public WDC5Writer(WDC5Reader reader, IDictionary<int, T> storage, Stream stream)
                 if (Flags.HasFlagExt(DB2Flags.Sparse))
                 {
                     long oldPos = writer.BaseStream.Position;
-                    writer.BaseStream.Position = 92;
+                    writer.BaseStream.Position = HeaderSize + 20;
                     writer.Write((uint)oldPos);
                     writer.BaseStream.Position = oldPos;
                 }
@@ -430,6 +429,10 @@ public WDC5Writer(WDC5Reader reader, IDictionary<int, T> storage, Stream stream)
                 if (Flags.HasFlagExt(DB2Flags.Sparse))
                     writer.WriteArray(SparseEntries.Values.ToArray());
 
+                // sparse data ids (if flag 0x2 is set)
+                if (Flags.HasFlagExt(DB2Flags.Sparse) && Flags.HasFlag(DB2Flags.SecondaryKey))
+                    writer.WriteArray(SparseEntries.Keys.ToArray());
+
                 // reference data
                 if (ReferenceData.Count > 0)
                 {
@@ -440,12 +443,15 @@ public WDC5Writer(WDC5Reader reader, IDictionary<int, T> storage, Stream stream)
                     for (int i = 0; i < ReferenceData.Count; i++)
                     {
                         writer.Write(ReferenceData[i]);
-                        writer.Write(i);
+                        if (Flags.HasFlag(DB2Flags.SecondaryKey))
+                            writer.Write(SparseEntries.Keys.ElementAt(i));
+                        else
+                            writer.Write(i);
                     }
                 }
 
-                // sparse data ids
-                if (Flags.HasFlagExt(DB2Flags.Sparse))
+                // sparse data ids (if flag 0x2 is not set)
+                if (Flags.HasFlagExt(DB2Flags.Sparse) && !Flags.HasFlag(DB2Flags.SecondaryKey))
                     writer.WriteArray(SparseEntries.Keys.ToArray());
             }
         }