diff --git a/src/sources/mssql/mssql-cast-rules.lisp b/src/sources/mssql/mssql-cast-rules.lisp
index 471740b..dec7ee8 100644
--- a/src/sources/mssql/mssql-cast-rules.lisp
+++ b/src/sources/mssql/mssql-cast-rules.lisp
@@ -125,7 +125,7 @@
       field
     (declare (ignore schema))           ; FIXME
     (let* ((ctype (mssql-column-ctype field))
-           (extra (when (mssql-column-identity field) "auto_increment"))
+           (extra (when (mssql-column-identity field) :auto-increment))
            (pgcol
             (apply-casting-rules table-name name type ctype default nullable extra)))
       ;; the MS SQL driver smartly maps data to the proper CL type, but the