diff --git a/programs/develop/libraries/libs-dev/libio/libio.asm b/programs/develop/libraries/libs-dev/libio/libio.asm
index f4d9fe7f92..61a4625daa 100644
--- a/programs/develop/libraries/libs-dev/libio/libio.asm
+++ b/programs/develop/libraries/libs-dev/libio/libio.asm
@@ -130,7 +130,7 @@ proc file.size _name ;//////////////////////////////////////////////////////////
 ;;------------------------------------------------------------------------------------------------;;
 ;> _name = path to file (full or relative) <asciiz>                                               ;;
 ;;------------------------------------------------------------------------------------------------;;
-;< eax = -1 (error) / file size (in bytes, up to 2G) <dword>                                      ;;
+;< ebx = -1 (error) / file size (in bytes, up to 2G) <dword>                                      ;;
 ;;------------------------------------------------------------------------------------------------;;
 ;# call `file.err` to obtain extended error information                                           ;;
 ;;================================================================================================;;