diff --git a/src/PeriodTraits/PeriodOperations.php b/src/PeriodTraits/PeriodOperations.php
index 292abad..a3ccd84 100644
--- a/src/PeriodTraits/PeriodOperations.php
+++ b/src/PeriodTraits/PeriodOperations.php
@@ -38,7 +38,9 @@ public function gap(Period $period): ?static
 
     public function overlap(Period ...$others): ?static
     {
-        if (count($others) > 1) {
+        if (count($others) === 0) {
+            return null;
+        } else if (count($others) > 1) {
             return $this->overlapAll(...$others);
         } else {
             $other = $others[0];
@@ -115,7 +117,9 @@ public function overlapAny(Period ...$others): PeriodCollection
      */
     public function subtract(Period ...$others): PeriodCollection
     {
-        if (count($others) > 1) {
+        if (count($others) === 0) {
+            return PeriodCollection::make($this);
+        } else if (count($others) > 1) {
             return $this->subtractAll(...$others);
         } else {
             $other = $others[0];
diff --git a/tests/Operations/OverlapTest.php b/tests/Operations/OverlapTest.php
index d65e770..1eb3f91 100644
--- a/tests/Operations/OverlapTest.php
+++ b/tests/Operations/OverlapTest.php
@@ -5,6 +5,7 @@
 use Generator;
 use PHPUnit\Framework\TestCase;
 use Spatie\Period\Period;
+use Spatie\Period\PeriodCollection;
 
 class OverlapTest extends TestCase
 {
@@ -178,4 +179,15 @@ public function noOverlappingDates()
          */
         yield [Period::make('2018-02-01', '2018-02-28'), Period::make('2018-01-01', '2018-01-31')];
     }
+
+    /** @test */
+    public function passing_empty_period_collection_returns_null()
+    {
+        $current = Period::make('2018-01-01', '2018-01-31');
+        $emptyCollection = new PeriodCollection;
+
+        $diff = $current->overlap(... $emptyCollection);
+
+        $this->assertNull($diff);
+    }
 }
diff --git a/tests/Operations/SubtractTest.php b/tests/Operations/SubtractTest.php
index 3789786..616a2e3 100644
--- a/tests/Operations/SubtractTest.php
+++ b/tests/Operations/SubtractTest.php
@@ -4,6 +4,7 @@
 
 use PHPUnit\Framework\TestCase;
 use Spatie\Period\Period;
+use Spatie\Period\PeriodCollection;
 
 class SubtractTest extends TestCase
 {
@@ -223,4 +224,17 @@ public function it_can_determine_multiple_diffs_for_sure()
         $this->assertTrue($diff[1]->equals(Period::make('2018-01-11', '2018-01-14')));
         $this->assertTrue($diff[2]->equals(Period::make('2018-01-21', '2018-01-31')));
     }
+
+    /** @test */
+    public function passing_empty_period_collection_returns_same_period_within_collection()
+    {
+        $current = Period::make('2018-01-01', '2018-01-31');
+        $emptyCollection = new PeriodCollection;
+
+        $diff = $current->subtract(... $emptyCollection);
+
+        $this->assertInstanceOf(PeriodCollection::class, $diff);
+        $this->assertCount(1, $diff);
+        $this->assertTrue($diff[0]->equals($current));
+    }
 }