diff --git a/lib/nntp/tiny/buffer.py b/lib/nntp/tiny/buffer.py
index 69c1ae1..d33b4b0 100644
--- a/lib/nntp/tiny/buffer.py
+++ b/lib/nntp/tiny/buffer.py
@@ -17,17 +17,25 @@ class OutputBuffer():
 
     def write(self, data: bytes):
         remaining = len(data)
+        offset_i  = 0
 
         while remaining > 0:
             needed = self.size - self.offset
             copy   = min(needed, remaining)
 
-            self.buf[self.offset:self.offset+copy] = data[0:copy]
+            start_i = offset_i
+            end_i   = start_i + copy
 
+            start_o = self.offset
+            end_o   = start_o + copy
+
+            self.buf[start_o:end_o] = data[start_i:end_i]
+
+            offset_i    += copy
             remaining   -= copy
             self.offset += copy
 
-            if self.offset >= self.size:
+            if self.offset == self.size:
                 self.sock.send(self.buf)
                 self.offset = 0