diff --git a/lib/Database.php b/lib/Database.php
index 856b6075..4da524a6 100644
--- a/lib/Database.php
+++ b/lib/Database.php
@@ -622,12 +622,12 @@ class Database {
                 arsse_articles.id as id,
                 arsse_articles.url as url,
                 title,author,content,guid,
-                DATEFORMAT(?, published) as published,
-                DATEFORMAT(?, edited) as edited,
+                DATEFORMAT(?, published) as published_date,
+                DATEFORMAT(?, edited) as edited_date,
                 DATEFORMAT(?, max(
                     modified, 
                     coalesce((select modified from arsse_marks join user on user is owner where article is arsse_articles.id),'')
-                )) as modified,
+                )) as modified_date,
                 NOT (select count(*) from arsse_marks join user on user is owner where article is arsse_articles.id and read is 1) as unread,
                 (select count(*) from arsse_marks join user on user is owner where article is arsse_articles.id and starred is 1) as starred,
                 (select max(id) from arsse_editions where article is arsse_articles.id) as edition,
@@ -665,8 +665,8 @@ class Database {
         if($context->oldestEdition()) $q->setWhere("edition >= ?", "int", $context->oldestEdition);
         if($context->latestEdition()) $q->setWhere("edition <= ?", "int", $context->latestEdition);
         // filter based on lastmod time
-        if($context->modifiedSince()) $q->setWhere("modified >= ?", "datetime", $context->modifiedSince);
-        if($context->notModifiedSince()) $q->setWhere("modified <= ?", "datetime", $context->notModifiedSince);
+        if($context->modifiedSince()) $q->setWhere("modified_date >= ?", "datetime", $context->modifiedSince);
+        if($context->notModifiedSince()) $q->setWhere("modified_date <= ?", "datetime", $context->notModifiedSince);
         // filter for un/read and un/starred status if specified
         if($context->unread()) $q->setWhere("unread is ?", "bool", $context->unread);
         if($context->starred()) $q->setWhere("starred is ?", "bool", $context->starred);
@@ -707,8 +707,8 @@ class Database {
         if($context->edition()) {
             // make sure the edition exists
             $edition = $this->articleValidateEdition($user, $context->edition);
-            // if the edition is not the latest, make no marks and return
-            if(!$edition['current']) return false;
+            // if the edition is not the latest, do not mark the read flag
+            if(!$edition['current']) $values[0] = null;
         } else if($context->article()) {
             // otherwise if an article context is specified, make sure it's valid
             $this->articleValidateId($user, $context->article);
@@ -722,7 +722,7 @@ class Database {
                     (select max(id) from arsse_editions where article is arsse_articles.id) as edition,
                     max(arsse_articles.modified, 
                         coalesce((select modified from arsse_marks join user on user is owner where article is arsse_articles.id),'')
-                    ) as modified,
+                    ) as modified_date,
                     (
                         not exists(select id from arsse_marks join user on user is owner where article is arsse_articles.id) 
                         and exists(select * from target_values where read is 1 or starred is 1)
@@ -744,8 +744,10 @@ class Database {
             // common table expression with the values to set
             $q->setCTE("target_values(read,starred) as (select ?,?)", ["bool","bool"], $values);
             if($context->edition()) {
+                // if an edition is specified, filter for its previously identified article
                 $q->setWhere("arsse_articles.id is ?", "int", $edition['article']);
             } else if($context->article()) {
+                // if an article is specified, filter for it (it has already been validated above)
                 $q->setWhere("arsse_articles.id is ?", "int", $context->article);
             } else if($context->subscription()) {
                 // if a subscription is specified, make sure it exists
@@ -767,8 +769,8 @@ class Database {
             if($context->oldestEdition()) $q->setWhere("edition >= ?", "int", $context->oldestEdition);
             if($context->latestEdition()) $q->setWhere("edition <= ?", "int", $context->latestEdition);
             // filter based on lastmod time
-            if($context->modifiedSince()) $q->setWhere("modified >= ?", "datetime", $context->modifiedSince);
-            if($context->notModifiedSince()) $q->setWhere("modified <= ?", "datetime", $context->notModifiedSince);
+            if($context->modifiedSince()) $q->setWhere("modified_date >= ?", "datetime", $context->modifiedSince);
+            if($context->notModifiedSince()) $q->setWhere("modified_date <= ?", "datetime", $context->notModifiedSince);
             // push the current query onto the CTE stack and execute the query we're actually interested in
             $q->pushCTE(
                 "target_articles(id,edition,modified,to_insert,to_update)", // CTE table specification
@@ -799,7 +801,7 @@ class Database {
         return $out;
     }
 
-    public function articleValidateEdition(string $user, int $id): array {
+    protected function articleValidateEdition(string $user, int $id): array {
         $out = $this->db->prepare(
             "SELECT 
                 arsse_editions.id as edition, 
diff --git a/lib/Misc/DateFormatter.php b/lib/Misc/DateFormatter.php
index 55438f5c..9039caaf 100644
--- a/lib/Misc/DateFormatter.php
+++ b/lib/Misc/DateFormatter.php
@@ -32,8 +32,11 @@ trait DateFormatter {
         } else if($date===null) {
             return null;
         } else if(is_string($date)) {
-            $time = strtotime($date);
-            if($time===false) return null;
+            try {
+                $time = (new \DateTime($date, new \DateTimeZone("UTC")))->getTimestamp();
+            } catch(\Throwable $e) {
+                return null;
+            }
         } else if (is_bool($date)) {
             return null;
         } else {
diff --git a/tests/lib/Database/SeriesArticle.php b/tests/lib/Database/SeriesArticle.php
index 9b2a507b..0dead0c8 100644
--- a/tests/lib/Database/SeriesArticle.php
+++ b/tests/lib/Database/SeriesArticle.php
@@ -178,9 +178,9 @@ trait SeriesArticle {
             'author' => '',
             'content' => '<p>Article content 1</p>',
             'guid' => 'e433653cef2e572eee4215fa299a4a5af9137b2cefd6283c85bd69a32915beda',
-            'published' => 946684800,
-            'edited' => 946684801,
-            'modified' => 946688400,
+            'published_date' => 946684800,
+            'edited_date' => 946684801,
+            'modified_date' => 946688400,
             'unread' => 1,
             'starred' => 0,
             'edition' => 101,
@@ -196,9 +196,9 @@ trait SeriesArticle {
             'author' => '',
             'content' => '<p>Article content 2</p>',
             'guid' => '5be8a5a46ecd52ed132191c8d27fb1af6b3d4edc00234c5d9f8f0e10562ed3b7',
-            'published' => 946771200,
-            'edited' => 946771202,
-            'modified' => 946778400,
+            'published_date' => 946771200,
+            'edited_date' => 946771202,
+            'modified_date' => 946778400,
             'unread' => 0,
             'starred' => 0,
             'edition' => 202,
@@ -214,9 +214,9 @@ trait SeriesArticle {
             'author' => '',
             'content' => '<p>Article content 3</p>',
             'guid' => '31a6594500a48b59fcc8a075ce82b946c9c3c782460d088bd7b8ef3ede97ad92',
-            'published' => 946857600,
-            'edited' => 946857603,
-            'modified' => 946868400,
+            'published_date' => 946857600,
+            'edited_date' => 946857603,
+            'modified_date' => 946868400,
             'unread' => 1,
             'starred' => 1,
             'edition' => 203,
@@ -232,9 +232,9 @@ trait SeriesArticle {
             'author' => '',
             'content' => '<p>Article content 4</p>',
             'guid' => '804e517d623390e71497982c77cf6823180342ebcd2e7d5e32da1e55b09dd180',
-            'published' => 946944000,
-            'edited' => 946944004,
-            'modified' => 946958400,
+            'published_date' => 946944000,
+            'edited_date' => 946944004,
+            'modified_date' => 946958400,
             'unread' => 0,
             'starred' => 1,
             'edition' => 204,
@@ -250,9 +250,9 @@ trait SeriesArticle {
             'author' => '',
             'content' => '<p>Article content 5</p>',
             'guid' => 'db3e736c2c492f5def5c5da33ddcbea1824040e9ced2142069276b0a6e291a41',
-            'published' => 947030400,
-            'edited' => 947030405,
-            'modified' => 947048400,
+            'published_date' => 947030400,
+            'edited_date' => 947030405,
+            'modified_date' => 947048400,
             'unread' => 1,
             'starred' => 0,
             'edition' => 305,
@@ -271,9 +271,17 @@ trait SeriesArticle {
             $this->data['arsse_articles']['rows'][] = [++$a,$b,null,null,null,null,null,null,null,"","","","2010-01-01T00:00:00Z"];
             $this->data['arsse_editions']['rows'][] = [$a,$a];
         }
+        $this->checkTables = ['arsse_marks' => ["owner","article","read","starred","modified"],];
         $this->user = "john.doe@example.net";
     }
 
+    protected function compareIds(array $exp, Context $c) {
+        $ids = array_column($ids = Data::$db->articleList($this->user, $c)->getAll(), "id");
+        sort($ids);
+        sort($exp);
+        $this->assertEquals($exp, $ids);
+    }
+
     function testListArticlesCheckingContext() {
         $this->user = "john.doe@example.com";
         // get all items for user
@@ -328,9 +336,7 @@ trait SeriesArticle {
     function testMarkAllArticlesUnread() {
         Data::$db->articleMark($this->user, ['read'=>false]);
         $now = $this->dateTransform(time(), "sql");
-        $state = $this->primeExpectations($this->data, [
-            'arsse_marks' => ["owner","article","read","starred","modified"],
-        ]);
+        $state = $this->primeExpectations($this->data, $this->checkTables);
         $state['arsse_marks']['rows'][9][2] = 0;
         $state['arsse_marks']['rows'][9][4] = $now;
         $state['arsse_marks']['rows'][11][2] = 0;
@@ -341,9 +347,7 @@ trait SeriesArticle {
     function testMarkAllArticlesRead() {
         Data::$db->articleMark($this->user, ['read'=>true]);
         $now = $this->dateTransform(time(), "sql");
-        $state = $this->primeExpectations($this->data, [
-            'arsse_marks' => ["owner","article","read","starred","modified"],
-        ]);
+        $state = $this->primeExpectations($this->data, $this->checkTables);
         $state['arsse_marks']['rows'][8][2] = 1;
         $state['arsse_marks']['rows'][8][4] = $now;
         $state['arsse_marks']['rows'][10][2] = 1;
@@ -358,9 +362,7 @@ trait SeriesArticle {
     function testMarkAllArticlesUnstarred() {
         Data::$db->articleMark($this->user, ['starred'=>false]);
         $now = $this->dateTransform(time(), "sql");
-        $state = $this->primeExpectations($this->data, [
-            'arsse_marks' => ["owner","article","read","starred","modified"],
-        ]);
+        $state = $this->primeExpectations($this->data, $this->checkTables);
         $state['arsse_marks']['rows'][10][3] = 0;
         $state['arsse_marks']['rows'][10][4] = $now;
         $state['arsse_marks']['rows'][11][3] = 0;
@@ -371,9 +373,7 @@ trait SeriesArticle {
     function testMarkAllArticlesStarred() {
         Data::$db->articleMark($this->user, ['starred'=>true]);
         $now = $this->dateTransform(time(), "sql");
-        $state = $this->primeExpectations($this->data, [
-            'arsse_marks' => ["owner","article","read","starred","modified"],
-        ]);
+        $state = $this->primeExpectations($this->data, $this->checkTables);
         $state['arsse_marks']['rows'][8][3] = 1;
         $state['arsse_marks']['rows'][8][4] = $now;
         $state['arsse_marks']['rows'][9][3] = 1;
@@ -388,9 +388,7 @@ trait SeriesArticle {
     function testMarkAllArticlesUnreadAndUnstarred() {
         Data::$db->articleMark($this->user, ['read'=>false,'starred'=>false]);
         $now = $this->dateTransform(time(), "sql");
-        $state = $this->primeExpectations($this->data, [
-            'arsse_marks' => ["owner","article","read","starred","modified"],
-        ]);
+        $state = $this->primeExpectations($this->data, $this->checkTables);
         $state['arsse_marks']['rows'][9][2] = 0;
         $state['arsse_marks']['rows'][9][4] = $now;
         $state['arsse_marks']['rows'][10][3] = 0;
@@ -404,9 +402,7 @@ trait SeriesArticle {
     function testMarkAllArticlesReadAndStarred() {
         Data::$db->articleMark($this->user, ['read'=>true,'starred'=>true]);
         $now = $this->dateTransform(time(), "sql");
-        $state = $this->primeExpectations($this->data, [
-            'arsse_marks' => ["owner","article","read","starred","modified"],
-        ]);
+        $state = $this->primeExpectations($this->data, $this->checkTables);
         $state['arsse_marks']['rows'][8][2] = 1;
         $state['arsse_marks']['rows'][8][3] = 1;
         $state['arsse_marks']['rows'][8][4] = $now;
@@ -424,9 +420,7 @@ trait SeriesArticle {
     function testMarkAllArticlesUnreadAndStarred() {
         Data::$db->articleMark($this->user, ['read'=>false,'starred'=>true]);
         $now = $this->dateTransform(time(), "sql");
-        $state = $this->primeExpectations($this->data, [
-            'arsse_marks' => ["owner","article","read","starred","modified"],
-        ]);
+        $state = $this->primeExpectations($this->data, $this->checkTables);
         $state['arsse_marks']['rows'][8][3] = 1;
         $state['arsse_marks']['rows'][8][4] = $now;
         $state['arsse_marks']['rows'][9][2] = 0;
@@ -444,9 +438,7 @@ trait SeriesArticle {
     function testMarkAllArticlesReadAndUnstarred() {
         Data::$db->articleMark($this->user, ['read'=>true,'starred'=>false]);
         $now = $this->dateTransform(time(), "sql");
-        $state = $this->primeExpectations($this->data, [
-            'arsse_marks' => ["owner","article","read","starred","modified"],
-        ]);
+        $state = $this->primeExpectations($this->data, $this->checkTables);
         $state['arsse_marks']['rows'][8][2] = 1;
         $state['arsse_marks']['rows'][8][4] = $now;
         $state['arsse_marks']['rows'][10][2] = 1;
@@ -464,9 +456,7 @@ trait SeriesArticle {
     function testMarkATreeFolder() {
         Data::$db->articleMark($this->user, ['read'=>true], (new Context)->folder(7));
         $now = $this->dateTransform(time(), "sql");
-        $state = $this->primeExpectations($this->data, [
-            'arsse_marks' => ["owner","article","read","starred","modified"],
-        ]);
+        $state = $this->primeExpectations($this->data, $this->checkTables);
         $state['arsse_marks']['rows'][] = [$this->user,5,1,0,$now];
         $state['arsse_marks']['rows'][] = [$this->user,6,1,0,$now];
         $state['arsse_marks']['rows'][] = [$this->user,7,1,0,$now];
@@ -477,9 +467,7 @@ trait SeriesArticle {
     function testMarkALeafFolder() {
         Data::$db->articleMark($this->user, ['read'=>true], (new Context)->folder(8));
         $now = $this->dateTransform(time(), "sql");
-        $state = $this->primeExpectations($this->data, [
-            'arsse_marks' => ["owner","article","read","starred","modified"],
-        ]);
+        $state = $this->primeExpectations($this->data, $this->checkTables);
         $state['arsse_marks']['rows'][] = [$this->user,5,1,0,$now];
         $state['arsse_marks']['rows'][] = [$this->user,6,1,0,$now];
         $this->compareExpectations($state);
@@ -493,9 +481,7 @@ trait SeriesArticle {
     function testMarkASubscription() {
         Data::$db->articleMark($this->user, ['read'=>true], (new Context)->subscription(13));
         $now = $this->dateTransform(time(), "sql");
-        $state = $this->primeExpectations($this->data, [
-            'arsse_marks' => ["owner","article","read","starred","modified"],
-        ]);
+        $state = $this->primeExpectations($this->data, $this->checkTables);
         $state['arsse_marks']['rows'][] = [$this->user,5,1,0,$now];
         $state['arsse_marks']['rows'][] = [$this->user,6,1,0,$now];
         $this->compareExpectations($state);
@@ -509,9 +495,7 @@ trait SeriesArticle {
     function testMarkAnArticle() {
         Data::$db->articleMark($this->user, ['starred'=>true], (new Context)->article(20));
         $now = $this->dateTransform(time(), "sql");
-        $state = $this->primeExpectations($this->data, [
-            'arsse_marks' => ["owner","article","read","starred","modified"],
-        ]);
+        $state = $this->primeExpectations($this->data, $this->checkTables);
         $state['arsse_marks']['rows'][9][3] = 1;
         $state['arsse_marks']['rows'][9][4] = $now;
         $this->compareExpectations($state);
@@ -525,19 +509,39 @@ trait SeriesArticle {
     function testMarkAnEdition() {
         Data::$db->articleMark($this->user, ['starred'=>true], (new Context)->edition(1001));
         $now = $this->dateTransform(time(), "sql");
-        $state = $this->primeExpectations($this->data, [
-            'arsse_marks' => ["owner","article","read","starred","modified"],
-        ]);
+        $state = $this->primeExpectations($this->data, $this->checkTables);
         $state['arsse_marks']['rows'][9][3] = 1;
         $state['arsse_marks']['rows'][9][4] = $now;
         $this->compareExpectations($state);
     }
 
-    function testMarkAStaleEdition() {
-        Data::$db->articleMark($this->user, ['starred'=>true], (new Context)->edition(20)); // no changes occur
-        $state = $this->primeExpectations($this->data, [
-            'arsse_marks' => ["owner","article","read","starred","modified"],
-        ]);
+    function testMarkAStaleEditionUnread() {
+        Data::$db->articleMark($this->user, ['read'=>false], (new Context)->edition(20)); // no changes occur
+        $state = $this->primeExpectations($this->data, $this->checkTables);
+        $this->compareExpectations($state);
+    }
+
+    function testMarkAStaleEditionStarred() {
+        Data::$db->articleMark($this->user, ['starred'=>true], (new Context)->edition(20));
+        $now = $this->dateTransform(time(), "sql");
+        $state = $this->primeExpectations($this->data, $this->checkTables);
+        $state['arsse_marks']['rows'][9][3] = 1;
+        $state['arsse_marks']['rows'][9][4] = $now;
+        $this->compareExpectations($state);
+    }
+
+    function testMarkAStaleEditionUnreadAndStarred() {
+        Data::$db->articleMark($this->user, ['read'=>false,'starred'=>true], (new Context)->edition(20)); // only starred is changed
+        $now = $this->dateTransform(time(), "sql");
+        $state = $this->primeExpectations($this->data, $this->checkTables);
+        $state['arsse_marks']['rows'][9][3] = 1;
+        $state['arsse_marks']['rows'][9][4] = $now;
+        $this->compareExpectations($state);
+    }
+
+    function testMarkAStaleEditionUnreadAndUnstarred() {
+        Data::$db->articleMark($this->user, ['read'=>false,'starred'=>false], (new Context)->edition(20)); // no changes occur
+        $state = $this->primeExpectations($this->data, $this->checkTables);
         $this->compareExpectations($state);
     }
 
@@ -546,10 +550,47 @@ trait SeriesArticle {
         Data::$db->articleMark($this->user, ['starred'=>true], (new Context)->edition(2));
     }
 
-    protected function compareIds(array $exp, Context $c) {
-        $ids = array_column($ids = Data::$db->articleList($this->user, $c)->getAll(), "id");
-        sort($ids);
-        sort($exp);
-        $this->assertEquals($exp, $ids);
+    function testMarkByOldestEdition() {
+        Data::$db->articleMark($this->user, ['starred'=>true], (new Context)->oldestEdition(19));
+        $now = $this->dateTransform(time(), "sql");
+        $state = $this->primeExpectations($this->data, $this->checkTables);
+        $state['arsse_marks']['rows'][8][3] = 1;
+        $state['arsse_marks']['rows'][8][4] = $now;
+        $state['arsse_marks']['rows'][9][3] = 1;
+        $state['arsse_marks']['rows'][9][4] = $now;
+        $this->compareExpectations($state);
+    }
+
+    function testMarkByLatestEdition() {
+        Data::$db->articleMark($this->user, ['starred'=>true], (new Context)->latestEdition(20));
+        $now = $this->dateTransform(time(), "sql");
+        $state = $this->primeExpectations($this->data, $this->checkTables);
+        $state['arsse_marks']['rows'][8][3] = 1;
+        $state['arsse_marks']['rows'][8][4] = $now;
+        $state['arsse_marks']['rows'][] = [$this->user,5,0,1,$now];
+        $state['arsse_marks']['rows'][] = [$this->user,6,0,1,$now];
+        $state['arsse_marks']['rows'][] = [$this->user,7,0,1,$now];
+        $state['arsse_marks']['rows'][] = [$this->user,8,0,1,$now];
+        $this->compareExpectations($state);
+    }
+
+    function testMarkByLastModified() {
+        Data::$db->articleMark($this->user, ['starred'=>true], (new Context)->modifiedSince('2017-01-01T00:00:00Z'));
+        $now = $this->dateTransform(time(), "sql");
+        $state = $this->primeExpectations($this->data, $this->checkTables);
+        $state['arsse_marks']['rows'][8][3] = 1;
+        $state['arsse_marks']['rows'][8][4] = $now;
+        $state['arsse_marks']['rows'][9][3] = 1;
+        $state['arsse_marks']['rows'][9][4] = $now;
+        $this->compareExpectations($state);
+    }
+
+    function testMarkByNotLastModified() {
+        Data::$db->articleMark($this->user, ['starred'=>true], (new Context)->notModifiedSince('2000-01-01T00:00:00Z'));
+        $now = $this->dateTransform(time(), "sql");
+        $state = $this->primeExpectations($this->data, $this->checkTables);
+        $state['arsse_marks']['rows'][] = [$this->user,5,0,1,$now];
+        $state['arsse_marks']['rows'][] = [$this->user,7,0,1,$now];
+        $this->compareExpectations($state);
     }
 }
\ No newline at end of file