--- ./date_api.module_original	2009-08-13 13:57:27.000000000 +0300
+++ ./date_api.module	2010-02-28 15:37:16.893709380 +0200
@@ -579,6 +579,7 @@
       $untranslated = array_flip(date_week_days_untranslated());
       break;
     case 'month_name':
+    case 'month_genitive':
     case 'month_abbr':
       $untranslated = array_flip(date_month_names_untranslated());
       break;  
@@ -625,7 +626,10 @@
   
   // These start with a pipe so the January value will be in position 1 instead of position 0.
   $replace[$langcode]['month_name'] = explode('|', trim(t('!month-name |January|February|March|April|May|June|July|August|September|October|November|December', array('!month-name' => ''), $langcode)));
+  $replace[$langcode]['month_genitive'] = explode('|', trim(t('!month-genitive |January|February|March|April|May|June|July|August|September|October|November|December', array('!month-name' => ''), $langcode)));
   $replace[$langcode]['month_abbr'] = explode('|', trim(t('!month-abbreviation |Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec', array('!month-abbreviation' => ''), $langcode)));
+
+
 }
 
 /**
@@ -680,7 +684,12 @@
         $datestring .= date_t(date_format($date, 'l'), 'day_abbr', $langcode);
         break;
       case 'F':
+        if ((strpos($format, 'd') === FALSE) && (strpos($format, 'j') === FALSE)) {
         $datestring .= date_t(date_format($date, 'F'), 'month_name', $langcode);
+        }
+        else {
+          $datestring .= date_t(date_format($date, 'F'), 'month_genitive', $langcode);
+        }
         break;  
       case 'M':
         $datestring .= date_t(date_format($date, 'F'), 'month_abbr', $langcode);