diff --git a/indra/llfilesystem/llfilesystem.cpp b/indra/llfilesystem/llfilesystem.cpp
index 2e2a97826c..c952cb2f1a 100644
--- a/indra/llfilesystem/llfilesystem.cpp
+++ b/indra/llfilesystem/llfilesystem.cpp
@@ -62,12 +62,20 @@ bool LLFileSystem::getExists(const LLUUID& file_id, const LLAssetType::EType fil
     const std::string extra_info = "";
     const std::string filename = LLDiskCache::getInstance()->metaDataToFilepath(id_str, file_type, extra_info);
 
-    llifstream file(filename, std::ios::binary);
-    if (file.is_open())
+    // <FS:Ansariel> IO-streams replacement
+    //llifstream file(filename, std::ios::binary);
+    //if (file.is_open())
+    //{
+    //    file.seekg(0, std::ios::end);
+    //    return file.tellg() > 0;
+    //}
+    llstat file_stat;
+    if (LLFile::stat(filename, &file_stat) == 0)
     {
-        file.seekg(0, std::ios::end);
-        return file.tellg() > 0;
+        return S_ISREG(file_stat.st_mode) && file_stat.st_size > 0;
     }
+    // </FS:Ansariel>
+
     return false;
 }
 
@@ -130,12 +138,19 @@ S32 LLFileSystem::getFileSize(const LLUUID& file_id, const LLAssetType::EType fi
     const std::string filename =  LLDiskCache::getInstance()->metaDataToFilepath(id_str, file_type, extra_info);
 
     S32 file_size = 0;
-    llifstream file(filename, std::ios::binary);
-    if (file.is_open())
+    // <FS:Ansariel> IO-streams replacement
+    //llifstream file(filename, std::ios::binary);
+    //if (file.is_open())
+    //{
+    //    file.seekg(0, std::ios::end);
+    //    file_size = file.tellg();
+    //}
+    llstat file_stat;
+    if (LLFile::stat(filename, &file_stat) == 0)
     {
-        file.seekg(0, std::ios::end);
-        file_size = file.tellg();
+        file_size = file_stat.st_size;
     }
+    // </FS:Ansariel>
 
     return file_size;
 }
@@ -149,23 +164,37 @@ BOOL LLFileSystem::read(U8* buffer, S32 bytes)
     const std::string extra_info = "";
     const std::string filename =  LLDiskCache::getInstance()->metaDataToFilepath(id, mFileType, extra_info);
 
-    llifstream file(filename, std::ios::binary);
-    if (file.is_open())
+    // <FS:Ansariel> IO-streams replacement
+    //llifstream file(filename, std::ios::binary);
+    //if (file.is_open())
+    //{
+    //    file.seekg(mPosition, std::ios::beg);
+
+    //    file.read((char*)buffer, bytes);
+
+    //    if (file)
+    //    {
+    //        mBytesRead = bytes;
+    //    }
+    //    else
+    //    {
+    //        mBytesRead = file.gcount();
+    //    }
+
+    //    file.close();
+
+    //    mPosition += mBytesRead;
+    //    if (!mBytesRead)
+    //    {
+    //        success = FALSE;
+    //    }
+    //}
+    LLFILE* file = LLFile::fopen(filename, "rb");
+    if (file)
     {
-        file.seekg(mPosition, std::ios::beg);
-
-        file.read((char*)buffer, bytes);
-
-        if (file)
-        {
-            mBytesRead = bytes;
-        }
-        else
-        {
-            mBytesRead = file.gcount();
-        }
-
-        file.close();
+        fseek(file, mPosition, SEEK_SET);
+        mBytesRead = fread(buffer, 1, bytes, file);
+        fclose(file);
 
         mPosition += mBytesRead;
         if (!mBytesRead)
@@ -173,6 +202,7 @@ BOOL LLFileSystem::read(U8* buffer, S32 bytes)
             success = FALSE;
         }
     }
+    // </FS:Ansariel>
 
     // update the last access time for the file - this is required
     // even though we are reading and not writing because this is the
@@ -202,55 +232,102 @@ BOOL LLFileSystem::write(const U8* buffer, S32 bytes)
 
     BOOL success = FALSE;
 
+    // <FS:Ansariel> IO-streams replacement
+    //if (mMode == APPEND)
+    //{
+    //    llofstream ofs(filename, std::ios::app | std::ios::binary);
+    //    if (ofs)
+    //    {
+    //        ofs.write((const char*)buffer, bytes);
+
+    //        mPosition = ofs.tellp(); // <FS:Ansariel> Fix asset caching
+
+    //        success = TRUE;
+    //    }
+    //}
+    //// <FS:Ansariel> Fix asset caching
+    //else if (mMode == READ_WRITE)
+    //{
+    //    // Don't truncate if file already exists
+    //    llofstream ofs(filename, std::ios::in | std::ios::binary);
+    //    if (ofs)
+    //    {
+    //        ofs.seekp(mPosition, std::ios::beg);
+    //        ofs.write((const char*)buffer, bytes);
+    //        mPosition += bytes;
+    //        success = TRUE;
+    //    }
+    //    else
+    //    {
+    //        // File doesn't exist - open in write mode
+    //        ofs.open(filename, std::ios::binary);
+    //        if (ofs.is_open())
+    //        {
+    //            ofs.write((const char*)buffer, bytes);
+    //            mPosition += bytes;
+    //            success = TRUE;
+    //        }
+    //    }
+    //}
+    //// </FS:Ansariel>
+    //else
+    //{
+    //    llofstream ofs(filename, std::ios::binary);
+    //    if (ofs)
+    //    {
+    //        ofs.write((const char*)buffer, bytes);
+
+    //        mPosition += bytes;
+
+    //        success = TRUE;
+    //    }
+    //}
     if (mMode == APPEND)
     {
-        llofstream ofs(filename, std::ios::app | std::ios::binary);
+        LLFILE* ofs = LLFile::fopen(filename, "a+b");
         if (ofs)
         {
-            ofs.write((const char*)buffer, bytes);
-
-            mPosition = ofs.tellp(); // <FS:Ansariel> Fix asset caching
-
+            fwrite(buffer, 1, bytes, ofs);
+            mPosition = ftell(ofs);
+            fclose(ofs);
             success = TRUE;
         }
     }
-    // <FS:Ansariel> Fix asset caching
     else if (mMode == READ_WRITE)
     {
-        // Don't truncate if file already exists
-        llofstream ofs(filename, std::ios::in | std::ios::binary);
+        LLFILE* ofs = LLFile::fopen(filename, "r+b");
         if (ofs)
         {
-            ofs.seekp(mPosition, std::ios::beg);
-            ofs.write((const char*)buffer, bytes);
-            mPosition += bytes;
+            fseek(ofs, mPosition, SEEK_SET);
+            fwrite(buffer, 1, bytes, ofs);
+            mPosition = ftell(ofs);
+            fclose(ofs);
             success = TRUE;
         }
         else
         {
-            // File doesn't exist - open in write mode
-            ofs.open(filename, std::ios::binary);
-            if (ofs.is_open())
+            ofs = LLFile::fopen(filename, "wb");
+            if (ofs)
             {
-                ofs.write((const char*)buffer, bytes);
-                mPosition += bytes;
+                fwrite(buffer, 1, bytes, ofs);
+                mPosition = ftell(ofs);
+                fclose(ofs);
                 success = TRUE;
             }
         }
     }
-    // </FS:Ansariel>
     else
     {
-        llofstream ofs(filename, std::ios::binary);
+        LLFILE* ofs = LLFile::fopen(filename, "wb");
         if (ofs)
         {
-            ofs.write((const char*)buffer, bytes);
-
-            mPosition += bytes;
-
+            fwrite(buffer, 1, bytes, ofs);
+            mPosition = ftell(ofs);
+            fclose(ofs);
             success = TRUE;
         }
     }
+    // </FS:Ansariel>
 
     return success;
 }