diff --git a/tests/Zval/Representation/MicrotimeRepresentationTest.php b/tests/Zval/Representation/MicrotimeRepresentationTest.php
index b99c39142..74d603e45 100644
--- a/tests/Zval/Representation/MicrotimeRepresentationTest.php
+++ b/tests/Zval/Representation/MicrotimeRepresentationTest.php
@@ -42,9 +42,6 @@ public function testConstruct()
     {
         $r = new MicrotimeRepresentation(123, 456, 7, 8, 100);
 
-        $mem = \memory_get_usage();
-        $mem_peak = \memory_get_peak_usage();
-
         $this->assertSame(123, $r->seconds);
         $this->assertSame(456, $r->microseconds);
         $this->assertSame(7, $r->group);
@@ -58,8 +55,8 @@ public function testConstruct()
         $this->assertSame(20.0, $r->avg);
 
         // Memory usage isn't going to be identical after making the representation
-        $this->assertLessThan(512, \abs($mem - $r->mem));
-        $this->assertSame($mem_peak, $r->mem_peak);
+        $this->assertLessThan(1024, abs(\memory_get_usage() - $r->mem));
+        $this->assertSame(\memory_get_peak_usage(), $r->mem_peak);
     }
 
     /**