diff --git a/doc/ca65.sgml b/doc/ca65.sgml
index 2e63e0961..d3905ab64 100644
--- a/doc/ca65.sgml
+++ b/doc/ca65.sgml
@@ -3897,7 +3897,7 @@ See: <tt><ref id=".ASCIIZ" name=".ASCIIZ"></tt>,<tt><ref id=".BYTE" name=".BYTE"
 
   Reserve storage. The command is followed by one or two constant
   expressions. The first one is mandatory and defines, how many bytes of
-  storage should be defined. The second, optional expression must by a
+  storage should be defined. The second, optional expression must be a
   constant byte value that will be used as value of the data. If there
   is no fill value given, the linker will use the value defined in the
   linker configuration file (default: zero).