diff --git a/src/RuleSet/DeclarationBlock.php b/src/RuleSet/DeclarationBlock.php
index 91f5ecef..e51e782f 100644
--- a/src/RuleSet/DeclarationBlock.php
+++ b/src/RuleSet/DeclarationBlock.php
@@ -735,7 +735,7 @@ public function createFontShorthand()
         if (!isset($aRules['font-size']) || !isset($aRules['font-family'])) {
             return;
         }
-        $oOldRule = isset($aRules['font-size']) ? $aRules['font-size'] : $aRules['font-family'];
+        $oOldRule = $aRules['font-size'] ?? $aRules['font-family'];
         $oNewRule = new Rule('font', $oOldRule->getLineNo(), $oOldRule->getColNo());
         unset($oOldRule);
         foreach (['font-style', 'font-variant', 'font-weight'] as $sProperty) {
diff --git a/src/Value/Size.php b/src/Value/Size.php
index f8336b1f..0ef3e6ac 100644
--- a/src/Value/Size.php
+++ b/src/Value/Size.php
@@ -219,6 +219,6 @@ public function render(OutputFormat $oOutputFormat)
         $sSize = preg_match("/[\d\.]+e[+-]?\d+/i", (string) $this->fSize)
             ? preg_replace("/$sPoint?0+$/", "", sprintf("%f", $this->fSize)) : $this->fSize;
         return preg_replace(["/$sPoint/", "/^(-?)0\./"], ['.', '$1.'], $sSize)
-            . ($this->sUnit === null ? '' : $this->sUnit);
+            . ($this->sUnit ?? '');
     }
 }