diff --git a/smart_open/azure.py b/smart_open/azure.py
index 96f944a1..ccc19059 100644
--- a/smart_open/azure.py
+++ b/smart_open/azure.py
@@ -306,7 +306,7 @@ def read(self, size=-1):
         if self._position == self._size:
             return self._read_from_buffer()
 
-        self._fill_buffer()
+        self._fill_buffer(size)
         return self._read_from_buffer(size)
 
     def read1(self, size=-1):