diff --git a/test/php/library/Icingadb/Util/PerfdataTest.php b/test/php/library/Icingadb/Util/PerfdataTest.php
index e31c86d00..7c904cfbe 100644
--- a/test/php/library/Icingadb/Util/PerfdataTest.php
+++ b/test/php/library/Icingadb/Util/PerfdataTest.php
@@ -399,4 +399,193 @@ public function testWhetherPercentagesAreHandledCorrectly()
             'Perfdata objects do not ignore impossible min/max combinations when returning percentages'
         );
     }
+
+    public function testWhetherInvalidValueInPerfDataHandledCorrectly()
+    {
+        $p1 = Perfdata::fromString('test=2,0');
+        $this->assertFalse($p1->isValid());
+        $this->assertNull(
+            $p1->getValue(),
+            'Perfdata::getValue does not return null for invalid values'
+        );
+        $this->assertSame(
+            '2,0',
+            $p1->toArray()['value']
+        );
+
+        $p2 = Perfdata::fromString('test=i am not a value');
+        $this->assertFalse($p2->isValid());
+        $this->assertNull(
+            $p2->getValue(),
+            'Perfdata::getValue does not return null for invalid values'
+        );
+        $this->assertSame(
+            'i am not a value',
+            $p2->toArray()['value']
+        );
+
+        $p3 = Perfdata::fromString('test=');
+        $this->assertFalse($p3->isValid());
+        $this->assertNull(
+            $p3->getValue(),
+            'Perfdata::getValue does not return null for invalid values'
+        );
+        $this->assertSame(
+            '',
+            $p3->toArray()['value']
+        );
+
+        $p4 = Perfdata::fromString('test=-kW');
+        $this->assertFalse($p4->isValid());
+        $this->assertNull(
+            $p4->getValue(),
+            'Perfdata::getValue does not return null for invalid values'
+        );
+        $this->assertSame(
+            '-kW',
+            $p4->toArray()['value']
+        );
+
+        $p5 = Perfdata::fromString('test=kW');
+        $this->assertFalse($p5->isValid());
+        $this->assertNull(
+            $p5->getValue(),
+            'Perfdata::getValue does not return null for invalid values'
+        );
+        $this->assertSame(
+            'kW',
+            $p5->toArray()['value']
+        );
+
+        $p6 = Perfdata::fromString('test=-');
+        $this->assertFalse($p6->isValid());
+        $this->assertNull(
+            $p6->getValue(),
+            'Perfdata::getValue does not return null for invalid values'
+        );
+        $this->assertSame(
+            '-',
+            $p6->toArray()['value']
+        );
+    }
+
+    public function testWhetherInvalidMinInPerfDataHandledCorrectly()
+    {
+        $p1 = Perfdata::fromString('test=1;;;2,0');
+        $this->assertFalse($p1->isValid());
+        $this->assertNull(
+            $p1->getMinimumValue(),
+            'Perfdata::getMinimumValue does not return null for invalid min values'
+        );
+        $this->assertSame(
+            '2,0',
+            $p1->toArray()['min']
+        );
+
+        $p2 = Perfdata::fromString('test=1;;;foo');
+        $this->assertFalse($p2->isValid());
+        $this->assertNull(
+            $p2->getMinimumValue(),
+            'Perfdata::getMinimumValue does not return null for invalid min values'
+        );
+        $this->assertSame(
+            'foo',
+            $p2->toArray()['min']
+        );
+    }
+
+    public function testWhetherInvalidMaxInPerfDataHandledCorrectly()
+    {
+        $p1 = Perfdata::fromString('test=1;;;;2,0');
+        $this->assertFalse($p1->isValid());
+        $this->assertNull(
+            $p1->getMaximumValue(),
+            'Perfdata::getMaximumValue does not return null for invalid max values'
+        );
+        $this->assertSame(
+            '2,0',
+            $p1->toArray()['max']
+        );
+
+        $p2 = Perfdata::fromString('test=1;;;;foo');
+        $this->assertFalse($p2->isValid());
+        $this->assertNull(
+            $p2->getMaximumValue(),
+            'Perfdata::getMaximumValue does not return null for invalid max values'
+        );
+        $this->assertSame(
+            'foo',
+            $p2->toArray()['max']
+        );
+    }
+
+    public function testWhetherInvalidWarningThresholdInPerfDataHandledCorrectly()
+    {
+        $p1 = Perfdata::fromString('test=1;2,0:');
+        $this->assertFalse($p1->getWarningThreshold()->isValid());
+        $this->assertFalse($p1->isValid());
+        $this->assertSame(
+            '2,0:',
+            (string) $p1->getWarningThreshold()
+        );
+
+        $p2 = Perfdata::fromString('test=1;0:4,0');
+        $this->assertFalse($p2->getWarningThreshold()->isValid());
+        $this->assertFalse($p2->isValid());
+        $this->assertSame(
+            '0:4,0',
+            (string) $p2->getWarningThreshold()
+        );
+
+        $p3 = Perfdata::fromString('test=1;foo');
+        $this->assertFalse($p2->getWarningThreshold()->isValid());
+        $this->assertFalse($p3->isValid());
+        $this->assertSame(
+            'foo',
+            (string) $p3->getWarningThreshold()
+        );
+
+        $p4 = Perfdata::fromString('test=1;10@');
+        $this->assertFalse($p2->getWarningThreshold()->isValid());
+        $this->assertFalse($p4->isValid());
+        $this->assertSame(
+            '10@',
+            (string) $p4->getWarningThreshold()
+        );
+    }
+
+    public function testWhetherInvalidCriticalThresholdInPerfDataHandledCorrectly()
+    {
+        $p1 = Perfdata::fromString('test=1;;2,0:');
+        $this->assertFalse($p1->getCriticalThreshold()->isValid());
+        $this->assertFalse($p1->isValid());
+        $this->assertSame(
+            '2,0:',
+            (string) $p1->getCriticalThreshold()
+        );
+
+        $p2 = Perfdata::fromString('test=1;;0:4,0');
+        $this->assertFalse($p2->getCriticalThreshold()->isValid());
+        $this->assertFalse($p2->isValid());
+        $this->assertSame(
+            '0:4,0',
+            (string) $p2->getCriticalThreshold()
+        );
+
+        $p3 = Perfdata::fromString('test=1;;foo');
+        $this->assertFalse($p2->getCriticalThreshold()->isValid());
+        $this->assertFalse($p3->isValid());
+        $this->assertSame(
+            'foo',
+            (string) $p3->getCriticalThreshold()
+        );
+
+        $p4 = Perfdata::fromString('test=1;10@');
+        $this->assertFalse($p2->getCriticalThreshold()->isValid());
+        $this->assertFalse($p4->isValid());
+        $this->assertSame(
+            '10@',
+            (string) $p4->getCriticalThreshold()
+        );
+    }
 }
diff --git a/test/php/library/Icingadb/Util/ThresholdRangeTest.php b/test/php/library/Icingadb/Util/ThresholdRangeTest.php
index c0d757371..b191e8804 100644
--- a/test/php/library/Icingadb/Util/ThresholdRangeTest.php
+++ b/test/php/library/Icingadb/Util/ThresholdRangeTest.php
@@ -319,5 +319,25 @@ public function testInvalidThresholdNotationsAreRenderedAsIs()
             'foo',
             (string) ThresholdRange::fromString('foo')
         );
+        $this->assertSame(
+            '4,4:2,2',
+            (string) ThresholdRange::fromString('4,4:2,2')
+        );
+    }
+
+    public function testInvalidThresholdNotationsConsideredInValid()
+    {
+        $this->assertFalse(
+            ThresholdRange::fromString('10@')->isValid(),
+            'Invalid threshold notation 10@ considered as valid'
+        );
+        $this->assertFalse(
+            ThresholdRange::fromString('foo')->isValid(),
+            'Invalid threshold notation foo considered as valid'
+        );
+        $this->assertFalse(
+            ThresholdRange::fromString('4,4:2,2')->isValid(),
+            'Invalid threshold notation 4,4:2,2 considered as valid'
+        );
     }
 }