diff --git a/testing/phpunit/ExpansionTest.php b/testing/phpunit/ExpansionTest.php
index 5a713186..7e5bf842 100644
--- a/testing/phpunit/ExpansionTest.php
+++ b/testing/phpunit/ExpansionTest.php
@@ -143,6 +143,10 @@ final class ExpansionTest extends TestCase
     '20190124T000000Z/20190124T010000Z',
   ];
 
+  /**
+   * @runInSeparateProcess
+   * @preserveGlobalState enabled
+   */
   public function testUnmodifiedCal() {
     global $base_cal;
 
@@ -152,6 +156,10 @@ final class ExpansionTest extends TestCase
     );
   }
 
+  /**
+   * @runInSeparateProcess
+   * @preserveGlobalState enabled
+   */
   public function testTueRenamed() {
     global $tuesday_renamed_cal;
 
@@ -161,6 +169,10 @@ final class ExpansionTest extends TestCase
     );
   }
 
+  /**
+   * @runInSeparateProcess
+   * @preserveGlobalState enabled
+   */
   public function testTueRenamedSwapped() {
     global $tuesday_renamed_cal_order_swapped;
 
@@ -170,6 +182,10 @@ final class ExpansionTest extends TestCase
     );
   }
 
+  /**
+   * @runInSeparateProcess
+   * @preserveGlobalState enabled
+   */
   public function testCalWithCount() {
     global $count_cal;
 
diff --git a/testing/phpunit/RangeTest.php b/testing/phpunit/RangeTest.php
index 5b865d5a..7c68d7a8 100644
--- a/testing/phpunit/RangeTest.php
+++ b/testing/phpunit/RangeTest.php
@@ -12,6 +12,10 @@ $c->rrule_loop_limit = 100;
 
 final class RangeTest extends TestCase
 {
+  /**
+   * @runInSeparateProcess
+   * @preserveGlobalState enabled
+   */
   public function testGetVCalendarRange() {
     $cal = new vCalendar("BEGIN:VCALENDAR
 PRODID:-//Mozilla.org/NONSGML Mozilla Calendar V1.1//EN
@@ -48,6 +52,10 @@ END:VCALENDAR");
     self::assertEquals("20190102T072000Z", (string) $range->until->UTC());
   }
 
+  /**
+   * @runInSeparateProcess
+   * @preserveGlobalState enabled
+   */
   public function testGetVCalendarRangeTwoDayAllDay() {
     $cal = new vCalendar("BEGIN:VCALENDAR
 PRODID:-//Mozilla.org/NONSGML Mozilla Calendar V1.1//EN
@@ -70,6 +78,10 @@ END:VCALENDAR");
     self::assertEquals("20190109T200000Z", (string) $range->until->UTC());
   }
 
+  /**
+   * @runInSeparateProcess
+   * @preserveGlobalState enabled
+   */
   public function testGetVCalendarRangeFloating() {
     // When interpreted as being in Greece, this event crosses the daylight savings boundary!
     // TODO deal with how that affects all-day events...
@@ -94,6 +106,10 @@ END:VCALENDAR");
     self::assertEquals("20181210T130000Z", (string) $range->until->UTC());
   }
 
+  /**
+   * @runInSeparateProcess
+   * @preserveGlobalState enabled
+   */
   public function testGetVCalendarRangeAllDayAcrossDST() {
     // When interpreted as being in Greece, this event crosses the daylight savings boundary!