diff --git a/application/config/routes.php b/application/config/routes.php
index da3a45f03..f6eafbcd2 100644
--- a/application/config/routes.php
+++ b/application/config/routes.php
@@ -75,16 +75,16 @@ $route['api/frontend/v1/stv/[sS]tudents/([WS]S[0-9]{4})/inout/outgoing'] = 'api/
 $route['api/frontend/v1/stv/[sS]tudents/([WS]S[0-9]{4})/inout/gemeinsamestudien'] = 'api/frontend/v1/stv/Students/getGemeinsamestudien';
 
 // (studiengang_kz)/prestudent[/(studiensemester_kurzbz)[/(filter)[/(otherfilter)]]]
-$route['api/frontend/v1/stv/[sS]tudents/(:num)/prestudent'] = 'api/frontend/v1/stv/Students/getPrestudents/$1';
-$route['api/frontend/v1/stv/[sS]tudents/(:num)/prestudent/([WS]S[0-9]{4})'] = 'api/frontend/v1/stv/Students/getPrestudents/$1/$2';
-$route['api/frontend/v1/stv/[sS]tudents/(:num)/prestudent/([WS]S[0-9]{4})/(:any)'] = 'api/frontend/v1/stv/Students/getPrestudents/$1/$2/$3';
-$route['api/frontend/v1/stv/[sS]tudents/(:num)/prestudent/([WS]S[0-9]{4})/(:any)/(:any)'] = 'api/frontend/v1/stv/Students/getPrestudents/$1/$2/$4';
+$route['api/frontend/v1/stv/[sS]tudents/(-?[0-9]+)/prestudent'] = 'api/frontend/v1/stv/Students/getPrestudents/$1';
+$route['api/frontend/v1/stv/[sS]tudents/(-?[0-9]+)/prestudent/([WS]S[0-9]{4})'] = 'api/frontend/v1/stv/Students/getPrestudents/$1/$2';
+$route['api/frontend/v1/stv/[sS]tudents/(-?[0-9]+)/prestudent/([WS]S[0-9]{4})/(:any)'] = 'api/frontend/v1/stv/Students/getPrestudents/$1/$2/$3';
+$route['api/frontend/v1/stv/[sS]tudents/(-?[0-9]+)/prestudent/([WS]S[0-9]{4})/(:any)/(:any)'] = 'api/frontend/v1/stv/Students/getPrestudents/$1/$2/$4';
 
 // (studiengang_kz)/(orgform)/prestudent[/(studiensemester_kurzbz)[/(filter)[/(otherfilter)]]]
-$route['api/frontend/v1/stv/[sS]tudents/(:num)/([A-Z]{2,3})/prestudent'] = 'api/frontend/v1/stv/Students/getPrestudentsOrgform/$1/$2';
-$route['api/frontend/v1/stv/[sS]tudents/(:num)/([A-Z]{2,3})/prestudent/([WS]S[0-9]{4})'] = 'api/frontend/v1/stv/Students/getPrestudentsOrgform/$1/$2/$3';
-$route['api/frontend/v1/stv/[sS]tudents/(:num)/([A-Z]{2,3})/prestudent/([WS]S[0-9]{4})/(:any)'] = 'api/frontend/v1/stv/Students/getPrestudentsOrgform/$1/$2/$3/$4';
-$route['api/frontend/v1/stv/[sS]tudents/(:num)/([A-Z]{2,3})/prestudent/([WS]S[0-9]{4})/(:any)/(:any)'] = 'api/frontend/v1/stv/Students/getPrestudentsOrgform/$1/$2/$3/$5';
+$route['api/frontend/v1/stv/[sS]tudents/(-?[0-9]+)/([A-Z]{2,3})/prestudent'] = 'api/frontend/v1/stv/Students/getPrestudentsOrgform/$1/$2';
+$route['api/frontend/v1/stv/[sS]tudents/(-?[0-9]+)/([A-Z]{2,3})/prestudent/([WS]S[0-9]{4})'] = 'api/frontend/v1/stv/Students/getPrestudentsOrgform/$1/$2/$3';
+$route['api/frontend/v1/stv/[sS]tudents/(-?[0-9]+)/([A-Z]{2,3})/prestudent/([WS]S[0-9]{4})/(:any)'] = 'api/frontend/v1/stv/Students/getPrestudentsOrgform/$1/$2/$3/$4';
+$route['api/frontend/v1/stv/[sS]tudents/(-?[0-9]+)/([A-Z]{2,3})/prestudent/([WS]S[0-9]{4})/(:any)/(:any)'] = 'api/frontend/v1/stv/Students/getPrestudentsOrgform/$1/$2/$3/$5';
 
 // (studiensemester_kurzbz)/(studiengang_kz)/(semester)/grp/(gruppe)
 $route['api/frontend/v1/stv/[sS]tudents/([WS]S[0-9]{4})/(-?[0-9]+)/(:num)/grp/(:any)'] = 'api/frontend/v1/stv/Students/getStudentsSpezialgruppe/$1/$2/$3/$4';