diff --git a/src/DateRange.php b/src/DateRange.php
index 2a66ddf..849e6a4 100644
--- a/src/DateRange.php
+++ b/src/DateRange.php
@@ -193,9 +193,9 @@ public function subtract($b)
         }
 
         if (
-            ($b->from && $this->includes($b->from))
+            ($b->from && $this->from != $b->from && $this->includes($b->from))
             ||
-            ($this->to && $b->includes($this->to))
+            ($this->to && $this->to != $b->to && $b->includes($this->to))
         ) {
             $from = $this->from;
             $to = (clone $b->from)->modify('-1 day');
diff --git a/tests/DateRange/Subtract.phpt b/tests/DateRange/Subtract.phpt
index e947258..c03c6f4 100644
--- a/tests/DateRange/Subtract.phpt
+++ b/tests/DateRange/Subtract.phpt
@@ -8,6 +8,7 @@ $range2 = \Danoha\DateRange::wrap([NULL, new \DateTime('2017-12-01'),]);
 $range3 = \Danoha\DateRange::wrap([new \DateTime('2017-01-01'), NULL,]);
 $range4 = \Danoha\DateRange::wrap([new \DateTime('2016-06-01'), new \DateTime('2017-05-31'),]);
 $range5 = \Danoha\DateRange::wrap([new \DateTime('2017-06-01'), new \DateTime('2018-05-31'),]);
+$range6 = \Danoha\DateRange::wrap([new \DateTime('2017-01-01'), new \DateTime('2017-05-31'),]);
 
 Assert::equal([
     ['from' => new \DateTime('2017-12-02'), 'to' => NULL,],
@@ -34,4 +35,8 @@ Assert::same([], $range1->subtract($range1)->unwrap());
 
 Assert::equal([
     ['from' => new \DateTime('2016-06-01'), 'to' => new \DateTime('2017-05-31'),],
-], $range4->subtract($range5)->unwrap());
\ No newline at end of file
+], $range4->subtract($range5)->unwrap());
+
+Assert::equal([
+	['from' => new \DateTime('2017-06-01'), 'to' => NULL,],
+], $range3->subtract($range6)->unwrap());
\ No newline at end of file