Index: deprecated.php
===================================================================
--- deprecated.php	(revision 37616)
+++ deprecated.php	(working copy)
@@ -3329,7 +3329,7 @@
 function wp_convert_bytes_to_hr( $bytes ) {
 	_deprecated_function( __FUNCTION__, '3.6', 'size_format()' );
 
-	$units = array( 0 => 'B', 1 => 'kB', 2 => 'MB', 3 => 'GB', 4 => 'TB' );
+	$units = array( 0 => 'B', 1 => 'KB', 2 => 'MB', 3 => 'GB', 4 => 'TB' );
 	$log   = log( $bytes, KB_IN_BYTES );
 	$power = (int) $log;
 	$size  = pow( KB_IN_BYTES, $log - $power );
Index: functions.php
===================================================================
--- functions.php	(revision 37616)
+++ functions.php	(working copy)
@@ -237,7 +237,7 @@
 /**
  * Convert number of bytes largest unit bytes will fit into.
  *
- * It is easier to read 1 kB than 1024 bytes and 1 MB than 1048576 bytes. Converts
+ * It is easier to read 1 KB than 1024 bytes and 1 MB than 1048576 bytes. Converts
  * number of bytes to human readable number by taking the number of that unit
  * that the bytes will go into it. Supports TB value.
  *
@@ -259,7 +259,7 @@
 		'TB' => TB_IN_BYTES,
 		'GB' => GB_IN_BYTES,
 		'MB' => MB_IN_BYTES,
-		'kB' => KB_IN_BYTES,
+		'KB' => KB_IN_BYTES,
 		'B'  => 1,
 	);