diff --git a/src/Disks/ReadIndirectBufferFromRemoteFS.cpp b/src/Disks/ReadIndirectBufferFromRemoteFS.cpp
index 2bbc2e2197e..960844e5281 100644
--- a/src/Disks/ReadIndirectBufferFromRemoteFS.cpp
+++ b/src/Disks/ReadIndirectBufferFromRemoteFS.cpp
@@ -87,10 +87,7 @@ bool ReadIndirectBufferFromRemoteFS<T>::nextImpl()
 {
     /// Find first available buffer that fits to given offset.
     if (!current_buf)
-    {
         current_buf = initialize();
-        pos = working_buffer.begin();
-    }
 
     /// If current buffer has remaining data - use it.
     if (current_buf)
@@ -115,10 +112,14 @@ bool ReadIndirectBufferFromRemoteFS<T>::nextImpl()
 template <typename T>
 bool ReadIndirectBufferFromRemoteFS<T>::nextAndShiftPosition()
 {
+    /// Transfer current position and working_buffer to actual ReadBuffer
     swap(*current_buf);
+    /// Position and working_buffer will be updated in next() call
     auto result = current_buf->next();
+    /// and assigned to current buffer.
     swap(*current_buf);
 
+    /// absolute position is shifted by a data size that was read in next() call above.
     if (result)
         absolute_position += working_buffer.size();
 
diff --git a/src/Disks/S3/DiskS3.cpp b/src/Disks/S3/DiskS3.cpp
index 3ca8e07bba6..33c0c2a7f52 100644
--- a/src/Disks/S3/DiskS3.cpp
+++ b/src/Disks/S3/DiskS3.cpp
@@ -320,6 +320,7 @@ void DiskS3::startup()
 {
     auto settings = current_settings.get();
 
+    /// Need to be enabled if it was disabled during shutdown() call.
     settings->client->EnableRequestProcessing();
 
     if (!settings->send_metadata)
diff --git a/src/IO/ReadBufferFromS3.cpp b/src/IO/ReadBufferFromS3.cpp
index 86cf44178eb..0e342fb846a 100644
--- a/src/IO/ReadBufferFromS3.cpp
+++ b/src/IO/ReadBufferFromS3.cpp
@@ -91,18 +91,15 @@ bool ReadBufferFromS3::nextImpl()
 
 off_t ReadBufferFromS3::seek(off_t offset_, int whence)
 {
+    if (impl)
+        throw Exception("Seek is allowed only before first read attempt from the buffer.", ErrorCodes::CANNOT_SEEK_THROUGH_FILE);
+
     if (whence != SEEK_SET)
         throw Exception("Only SEEK_SET mode is allowed.", ErrorCodes::CANNOT_SEEK_THROUGH_FILE);
 
     if (offset_ < 0)
         throw Exception("Seek position is out of bounds. Offset: " + std::to_string(offset_), ErrorCodes::SEEK_POSITION_OUT_OF_BOUND);
 
-    if (impl)
-    {
-        impl.reset();
-        pos = working_buffer.end();
-    }
-
     offset = offset_;
 
     return offset;