diff --git a/includes/controller/shift_entries_controller.php b/includes/controller/shift_entries_controller.php
index 148b19fb..150db2e9 100644
--- a/includes/controller/shift_entries_controller.php
+++ b/includes/controller/shift_entries_controller.php
@@ -13,7 +13,7 @@ function shift_entry_add_controller()
 
     $request = request();
     $shift_id = 0;
-    if ($request->has('shift_id') && preg_match('/^\d*$/', $request->input('shift_id'))) {
+    if ($request->has('shift_id') && preg_match('/^\d+$/', $request->input('shift_id'))) {
         $shift_id = $request->input('shift_id');
     } else {
         redirect(page_link_to('user_shifts'));
@@ -33,7 +33,7 @@ function shift_entry_add_controller()
     $shift['Name'] = $room_array[$shift['RID']];
 
     $type_id = 0;
-    if ($request->has('type_id') && preg_match('/^\d*$/', $request->input('type_id'))) {
+    if ($request->has('type_id') && preg_match('/^\d+$/', $request->input('type_id'))) {
         $type_id = $request->input('type_id');
     } else {
         redirect(page_link_to('user_shifts'));
@@ -64,7 +64,7 @@ function shift_entry_add_controller()
 
     if (
         $request->has('user_id')
-        && preg_match('/^\d*$/', $request->input('user_id'))
+        && preg_match('/^\d+$/', $request->input('user_id'))
         && (
             in_array('user_shifts_admin', $privileges)
             || in_array('shiftentry_edit_angeltype_supporter', $privileges)
diff --git a/includes/controller/shifts_controller.php b/includes/controller/shifts_controller.php
index c359850f..70011821 100644
--- a/includes/controller/shifts_controller.php
+++ b/includes/controller/shifts_controller.php
@@ -8,10 +8,13 @@ use Engelsystem\ShiftSignupState;
  */
 function shift_link($shift)
 {
-    $link = page_link_to('shifts', ['action' => 'view']);
+    $parameters = ['action' => 'view'];
     if (isset($shift['SID'])) {
-        $link .= '&shift_id=' . $shift['SID'];
+        $parameters['shift_id'] = $shift['SID'];
     }
+
+    $link = page_link_to('shifts', $parameters);
+
     return $link;
 }
 
@@ -201,7 +204,7 @@ function shift_delete_controller()
     }
 
     // Schicht komplett löschen (nur für admins/user mit user_shifts_admin privileg)
-    if (!$request->has('delete_shift') || !preg_match('/^\d*$/', $request->input('delete_shift'))) {
+    if (!$request->has('delete_shift') || !preg_match('/^\d+$/', $request->input('delete_shift'))) {
         redirect(page_link_to('user_shifts'));
     }
     $shift_id = $request->input('delete_shift');
@@ -316,8 +319,6 @@ function shifts_controller()
 
 /**
  * Redirects the user to his next shift.
- *
- * @return false
  */
 function shift_next_controller()
 {
diff --git a/includes/pages/admin_arrive.php b/includes/pages/admin_arrive.php
index 2f312b1f..48e2c91f 100644
--- a/includes/pages/admin_arrive.php
+++ b/includes/pages/admin_arrive.php
@@ -23,7 +23,7 @@ function admin_arrive()
         $search = strip_request_item('search');
     }
 
-    if ($request->has('reset') && preg_match('/^\d*$/', $request->input('reset'))) {
+    if ($request->has('reset') && preg_match('/^\d+$/', $request->input('reset'))) {
         $user_id = $request->input('reset');
         $user_source = User($user_id);
         if ($user_source != null) {
@@ -39,7 +39,7 @@ function admin_arrive()
         } else {
             $msg = error(_('Angel not found.'), true);
         }
-    } elseif ($request->has('arrived') && preg_match('/^\d*$/', $request->input('arrived'))) {
+    } elseif ($request->has('arrived') && preg_match('/^\d+$/', $request->input('arrived'))) {
         $user_id = $request->input('arrived');
         $user_source = User($user_id);
         if ($user_source != null) {
diff --git a/includes/pages/admin_import.php b/includes/pages/admin_import.php
index bf8c498c..e97f95e1 100644
--- a/includes/pages/admin_import.php
+++ b/includes/pages/admin_import.php
@@ -98,10 +98,12 @@ function admin_import()
 
             if ($valid) {
                 redirect(
-                    page_link_to('admin_import')
-                    . '&step=check&shifttype_id=' . $shifttype_id
-                    . '&add_minutes_end=' . $add_minutes_end
-                    . '&add_minutes_start=' . $add_minutes_start
+                    page_link_to('admin_import', [
+                        'step'              => 'check',
+                        'shifttype_id'      => $shifttype_id,
+                        'add_minutes_end'   => $add_minutes_end,
+                        'add_minutes_start' => $add_minutes_start,
+                    ])
                 );
             } else {
                 $html .= div('well well-sm text-center', [
@@ -207,10 +209,12 @@ function admin_import()
                         ], shifts_printable($events_deleted, $shifttypes)),
                         form_submit('submit', _('Import'))
                     ],
-                    page_link_to('admin_import')
-                    . '&step=import&shifttype_id=' . $shifttype_id
-                    . '&add_minutes_end=' . $add_minutes_end
-                    . '&add_minutes_start=' . $add_minutes_start
+                    page_link_to('admin_import', [
+                        'step'              => 'import',
+                        'shifttype_id'      => $shifttype_id,
+                        'add_minutes_end'   => $add_minutes_end,
+                        'add_minutes_start' => $add_minutes_start,
+                    ])
                 );
             break;
 
diff --git a/includes/pages/admin_user.php b/includes/pages/admin_user.php
index 9b3b0f44..0620155b 100644
--- a/includes/pages/admin_user.php
+++ b/includes/pages/admin_user.php
@@ -179,11 +179,11 @@ function admin_user()
         switch ($request->input('action')) {
             case 'save_groups':
                 if ($user_id != $user['UID']) {
-                    $my_highest_group = DB::select(
+                    $my_highest_group = DB::selectOne(
                         'SELECT * FROM `UserGroups` WHERE `uid`=? ORDER BY `group_id`',
                         [$user['UID']]
                     );
-                    $his_highest_group = DB::select(
+                    $his_highest_group = DB::selectOne(
                         'SELECT * FROM `UserGroups` WHERE `uid`=? ORDER BY `group_id`',
                         [$user_id]
                     );
diff --git a/includes/pages/user_myshifts.php b/includes/pages/user_myshifts.php
index 60a26922..836bd566 100644
--- a/includes/pages/user_myshifts.php
+++ b/includes/pages/user_myshifts.php
@@ -46,7 +46,7 @@ function user_myshifts()
             ),
             button(page_link_to('user_myshifts', ['reset' => 'ack']), _('Continue'), 'btn-danger')
         ]);
-    } elseif ($request->has('edit') && preg_match('/^\d*$/', $request->input('edit'))) {
+    } elseif ($request->has('edit') && preg_match('/^\d+$/', $request->input('edit'))) {
         $user_id = $request->input('edit');
         $shift = DB::selectOne('
                 SELECT
@@ -124,7 +124,7 @@ function user_myshifts()
         } else {
             redirect(page_link_to('user_myshifts'));
         }
-    } elseif ($request->has('cancel') && preg_match('/^\d*$/', $request->input('cancel'))) {
+    } elseif ($request->has('cancel') && preg_match('/^\d+$/', $request->input('cancel'))) {
         $user_id = $request->input('cancel');
         $shift = DB::selectOne('
                 SELECT *
diff --git a/includes/sys_page.php b/includes/sys_page.php
index df57d08a..33ec18b9 100644
--- a/includes/sys_page.php
+++ b/includes/sys_page.php
@@ -170,7 +170,11 @@ function strip_request_item($name, $default_value = null)
 function test_request_int($name)
 {
     $input = request()->input($name);
-    return preg_match('/^\d*$/', $input);
+    if (is_null($input)) {
+        return false;
+    }
+
+    return preg_match('/^\d+$/', $input);
 }
 
 /**
diff --git a/includes/view/Rooms_view.php b/includes/view/Rooms_view.php
index 76ce33a5..3c0440a4 100644
--- a/includes/view/Rooms_view.php
+++ b/includes/view/Rooms_view.php
@@ -12,7 +12,7 @@ use Engelsystem\ShiftsFilterRenderer;
 function Room_view($room, ShiftsFilterRenderer $shiftsFilterRenderer, ShiftCalendarRenderer $shiftCalendarRenderer)
 {
     return page_with_title(glyph('map-marker') . $room['Name'], [
-        $shiftsFilterRenderer->render(room_link($room)),
+        $shiftsFilterRenderer->render($room),
         $shiftCalendarRenderer->render()
     ]);
 }
diff --git a/includes/view/ShiftCalendarShiftRenderer.php b/includes/view/ShiftCalendarShiftRenderer.php
index f0488e83..0e5fc8c3 100644
--- a/includes/view/ShiftCalendarShiftRenderer.php
+++ b/includes/view/ShiftCalendarShiftRenderer.php
@@ -124,11 +124,15 @@ class ShiftCalendarShiftRenderer
         }
 
         if (in_array('user_shifts_admin', $privileges)) {
-            $html .= '<li class="list-group-item">' . button(
-                    page_link_to('user_shifts', ['shift_id' => $shift['SID']]),
-                    _('Add more angels'),
-                    'btn-xs'
-                ) . '</li>';
+            $html .= '<li class="list-group-item">' . _('Add more angels') . ':';
+            foreach ($needed_angeltypes as $angeltype) {
+                $html .= ' ' . button(
+                        page_link_to('user_shifts', ['shift_id' => $shift['SID'], 'type_id' => $angeltype['id']]),
+                        $angeltype['name'],
+                        'btn-xs'
+                    );
+            }
+            $html .= '</li>';
         }
         if ($html != '') {
             return [
diff --git a/includes/view/ShiftsFilterRenderer.php b/includes/view/ShiftsFilterRenderer.php
index 43a23ef6..c3e0ccf1 100644
--- a/includes/view/ShiftsFilterRenderer.php
+++ b/includes/view/ShiftsFilterRenderer.php
@@ -39,17 +39,22 @@ class ShiftsFilterRenderer
     /**
      * Renders the filter.
      *
-     * @param string $link_base
+     * @param array $room
      * @return string Generated HTML
      */
-    public function render($link_base)
+    public function render($room)
     {
         $toolbar = [];
         if ($this->daySelectionEnabled && !empty($this->days)) {
             $selected_day = date('Y-m-d', $this->shiftsFilter->getStartTime());
             $day_dropdown_items = [];
             foreach ($this->days as $day) {
-                $day_dropdown_items[] = toolbar_item_link($link_base . '&shifts_filter_day=' . $day, '', $day);
+                $link = page_link_to('rooms', [
+                    'action'            => 'view',
+                    'room_id'           => $room['RID'],
+                    'shifts_filter_day' => $day,
+                ]);
+                $day_dropdown_items[] = toolbar_item_link($link, '', $day);
             }
             $toolbar[] = toolbar_dropdown('', $selected_day, $day_dropdown_items, 'active');
         }