\RequirePackage{filehook}
\newif\ifGm@ltj@layoutswitch
\let\orig@PackageWarningNoLine=\PackageWarningNoLine
-\ifdefined\ifGm@swap@papersize\else\newif\ifGm@swap@papersize\fi
+% define ifGm@swap@papersize if it is undefined
+\expandafter\newif\csname ifGm@swap@papersize\endcsname
\AtBeginOfPackageFile{geometry}{%
\edef\Gm@ltj@topskip{\the\topskip}