diff --git a/r5dev/vpklib/packedstore.cpp b/r5dev/vpklib/packedstore.cpp
index 6575f252..638a5aab 100644
--- a/r5dev/vpklib/packedstore.cpp
+++ b/r5dev/vpklib/packedstore.cpp
@@ -999,8 +999,20 @@ CUtlString VPKDir_t::StripLocalePrefix(const CUtlString& directoryPath) const
 // Purpose: writes the vpk directory header
 // Input  : hDirectoryFile - 
 //-----------------------------------------------------------------------------
-void VPKDir_t::WriteHeader(FileHandle_t hDirectoryFile) const
+void VPKDir_t::WriteHeader(FileHandle_t hDirectoryFile)
 {
+	// Header versions.
+	m_Header.m_nHeaderMarker = VPK_HEADER_MARKER;
+	m_Header.m_nMajorVersion = VPK_MAJOR_VERSION;
+	m_Header.m_nMinorVersion = VPK_MINOR_VERSION;
+
+	// NOTE: directory size does not include header!
+	m_Header.m_nDirectorySize = static_cast<uint32_t>(FileSystem()->Tell(hDirectoryFile) - sizeof(VPKDirHeader_t));
+	m_Header.m_nSignatureSize = NULL;
+
+	// Seek to start of file to write out the header.
+	FileSystem()->Seek(hDirectoryFile, 0, FileSystemSeek_t::FILESYSTEM_SEEK_HEAD);
+
 	FileSystem()->Write(&m_Header.m_nHeaderMarker, sizeof(uint32_t), hDirectoryFile);
 	FileSystem()->Write(&m_Header.m_nMajorVersion, sizeof(uint16_t), hDirectoryFile);
 	FileSystem()->Write(&m_Header.m_nMinorVersion, sizeof(uint16_t), hDirectoryFile);
@@ -1008,17 +1020,6 @@ void VPKDir_t::WriteHeader(FileHandle_t hDirectoryFile) const
 	FileSystem()->Write(&m_Header.m_nSignatureSize, sizeof(uint32_t), hDirectoryFile);
 }
 
-//-----------------------------------------------------------------------------
-// Purpose: writes the directory tree size
-// Input  : hDirectoryFile - 
-//-----------------------------------------------------------------------------
-void VPKDir_t::WriteTreeSize(FileHandle_t hDirectoryFile) const
-{
-	FileSystem()->Seek(hDirectoryFile, offsetof(VPKDir_t, m_Header.m_nDirectorySize), FileSystemSeek_t::FILESYSTEM_SEEK_HEAD);
-	FileSystem()->Write(&m_Header.m_nDirectorySize, sizeof(uint32_t), hDirectoryFile);
-	FileSystem()->Write(&PACKFILEINDEX_SEP, sizeof(uint32_t), hDirectoryFile);
-}
-
 //-----------------------------------------------------------------------------
 // Purpose: builds the vpk directory tree
 // Input  : &entryBlocks - 
@@ -1159,13 +1160,13 @@ void VPKDir_t::BuildDirectoryFile(const CUtlString& directoryPath, const CUtlVec
 	CTreeBuilder treeBuilder;
 	treeBuilder.BuildTree(entryBlocks);
 
+	// Seek to leave space for header after we wrote the tree.
+	FileSystem()->Seek(hDirectoryFile, sizeof(VPKDirHeader_t), FileSystemSeek_t::FILESYSTEM_SEEK_HEAD);
+	const int nDescriptors = treeBuilder.WriteTree(hDirectoryFile);
+
 	WriteHeader(hDirectoryFile);
-	int nDescriptors = treeBuilder.WriteTree(hDirectoryFile);
-
-	m_Header.m_nDirectorySize = static_cast<uint32_t>(FileSystem()->Tell(hDirectoryFile) - sizeof(VPKDirHeader_t));
-	WriteTreeSize(hDirectoryFile);
-
 	FileSystem()->Close(hDirectoryFile);
+
 	Msg(eDLL_T::FS, "*** Build directory totaling '%zu' bytes with '%i' entries and '%i' descriptors\n",
 		size_t(sizeof(VPKDirHeader_t) + m_Header.m_nDirectorySize), entryBlocks.Count(), nDescriptors);
 }
diff --git a/r5dev/vpklib/packedstore.h b/r5dev/vpklib/packedstore.h
index 10a59ae0..da14321a 100644
--- a/r5dev/vpklib/packedstore.h
+++ b/r5dev/vpklib/packedstore.h
@@ -162,9 +162,9 @@ struct VPKDir_t
 
 	VPKDir_t()
 	{
-		m_Header.m_nHeaderMarker = VPK_HEADER_MARKER; m_Header.m_nMajorVersion = VPK_MAJOR_VERSION;
-		m_Header.m_nMinorVersion = VPK_MINOR_VERSION; m_Header.m_nDirectorySize = NULL, m_Header.m_nSignatureSize = NULL;
-		m_bInitFailed = false;
+		m_Header.m_nHeaderMarker = NULL; m_Header.m_nMajorVersion = NULL;
+		m_Header.m_nMinorVersion = NULL; m_Header.m_nDirectorySize = NULL,
+		m_Header.m_nSignatureSize = NULL; m_bInitFailed = false;
 	};
 	VPKDir_t(const CUtlString& svDirectoryFile);
 	VPKDir_t(const CUtlString& svDirectoryFile, bool bSanitizeName);
@@ -175,9 +175,7 @@ struct VPKDir_t
 	CUtlString StripLocalePrefix(const CUtlString& svDirectoryFile) const;
 	CUtlString GetPackFileNameForIndex(uint16_t iPackFileIndex) const;
 
-	void WriteHeader(FileHandle_t hDirectoryFile) const;
-	void WriteTreeSize(FileHandle_t hDirectoryFile) const;
-
+	void WriteHeader(FileHandle_t hDirectoryFile);
 	void BuildDirectoryFile(const CUtlString& svDirectoryFile, const CUtlVector<VPKEntryBlock_t>& entryBlocks);
 };