diff --git a/lib/Ebook.php b/lib/Ebook.php
index 542b9c87..55ad8550 100644
--- a/lib/Ebook.php
+++ b/lib/Ebook.php
@@ -143,13 +143,21 @@ class Ebook{
 		}
 		$hash = substr(sha1($this->GitCommits[0]->Timestamp->format('U') . ' ' . $this->GitCommits[0]->Message), 0, 8);
 		$this->CoverImageUrl = '/images/covers/' . $this->UrlSafeIdentifier . '-' . $hash . '-cover.jpg';
-		$this->CoverImageAvifUrl = '/images/covers/' . $this->UrlSafeIdentifier . '-' . $hash . '-cover.avif';
+		if(file_exists(WEB_ROOT . '/images/covers/' . $this->UrlSafeIdentifier . '-cover.avif')){
+			$this->CoverImageAvifUrl = '/images/covers/' . $this->UrlSafeIdentifier . '-' . $hash . '-cover.avif';
+		}
 		$this->CoverImage2xUrl = '/images/covers/' . $this->UrlSafeIdentifier . '-' . $hash . '-cover@2x.jpg';
-		$this->CoverImage2xAvifUrl = '/images/covers/' . $this->UrlSafeIdentifier . '-' . $hash . '-cover@2x.avif';
+		if(file_exists(WEB_ROOT . '/images/covers/' . $this->UrlSafeIdentifier . '-cover@2x.avif')){
+			$this->CoverImage2xAvifUrl = '/images/covers/' . $this->UrlSafeIdentifier . '-' . $hash . '-cover@2x.avif';
+		}
 		$this->HeroImageUrl = '/images/covers/' . $this->UrlSafeIdentifier . '-' . $hash . '-hero.jpg';
-		$this->HeroImageAvifUrl = '/images/covers/' . $this->UrlSafeIdentifier . '-' . $hash . '-hero.avif';
+		if(file_exists(WEB_ROOT . '/images/covers/' . $this->UrlSafeIdentifier . '-hero.avif')){
+			$this->HeroImageAvifUrl = '/images/covers/' . $this->UrlSafeIdentifier . '-' . $hash . '-hero.avif';
+		}
 		$this->HeroImage2xUrl = '/images/covers/' . $this->UrlSafeIdentifier . '-' . $hash . '-hero@2x.jpg';
-		$this->HeroImage2xAvifUrl = '/images/covers/' . $this->UrlSafeIdentifier . '-' . $hash . '-hero@2x.avif';
+		if(file_exists(WEB_ROOT . '/images/covers/' . $this->UrlSafeIdentifier . '-hero@2x.avif')){
+			$this->HeroImage2xAvifUrl = '/images/covers/' . $this->UrlSafeIdentifier . '-' . $hash . '-hero@2x.avif';
+		}
 
 		// Now do some heavy XML lifting!
 		$xml = new SimpleXMLElement(str_replace('xmlns=', 'ns=', $rawMetadata));
diff --git a/templates/EbookGrid.php b/templates/EbookGrid.php
index cfbede62..0fda5f74 100644
--- a/templates/EbookGrid.php
+++ b/templates/EbookGrid.php
@@ -8,7 +8,7 @@ if(!isset($ebooks)){
 	<li>
 		<a href="<?= $ebook->Url ?>">
 			<picture>
-				<source srcset="<?= $ebook->CoverImage2xAvifUrl ?> 2x, <?= $ebook->CoverImageAvifUrl ?> 1x" type="image/avif">
+				<? if($ebook->CoverImage2xAvifUrl !== null){ ?><source srcset="<?= $ebook->CoverImage2xAvifUrl ?> 2x, <?= $ebook->CoverImageAvifUrl ?> 1x" type="image/avif"><? } ?>
 				<source srcset="<?= $ebook->CoverImage2xUrl ?> 2x, <?= $ebook->CoverImageUrl ?> 1x" type="image/jpg">
 				<img src="<?= $ebook->CoverImage2xUrl ?>" title="<?= Formatter::ToPlainText($ebook->Title) ?>" alt="The cover for the Standard Ebooks edition of <?= Formatter::ToPlainText(strip_tags($ebook->TitleWithCreditsHtml)) ?>" />
 			</picture>
diff --git a/www/ebooks/ebook.php b/www/ebooks/ebook.php
index 02d8647a..a122e2ff 100644
--- a/www/ebooks/ebook.php
+++ b/www/ebooks/ebook.php
@@ -79,7 +79,7 @@ catch(\Exception $ex){
 				<? } ?>
 			</div>
 			<picture>
-				<source srcset="<?= $ebook->HeroImage2xAvifUrl ?> 2x, <?= $ebook->HeroImageAvifUrl ?> 1x" type="image/avif">
+				<? if($ebook->HeroImage2xAvifUrl !== null){ ?><source srcset="<?= $ebook->HeroImage2xAvifUrl ?> 2x, <?= $ebook->HeroImageAvifUrl ?> 1x" type="image/avif"><? } ?>
 				<source srcset="<?= $ebook->HeroImage2xUrl ?> 2x, <?= $ebook->HeroImageUrl ?> 1x" type="image/jpg">
 				<img src="<?= $ebook->HeroImage2xUrl ?>" alt="The cover for the Standard Ebooks edition of <?= Formatter::ToPlainText(strip_tags($ebook->TitleWithCreditsHtml)) ?>">
 			</picture>
@@ -202,7 +202,7 @@ catch(\Exception $ex){
 				<li>
 					<a href="<?= $carouselEbook->Url ?>">
 						<picture>
-							<source srcset="<?= $carouselEbook->CoverImage2xAvifUrl ?> 2x, <?= $carouselEbook->CoverImageAvifUrl ?> 1x" type="image/avif">
+							<? if($carouselEbook->CoverImage2xAvifUrl !== null){ ?><source srcset="<?= $carouselEbook->CoverImage2xAvifUrl ?> 2x, <?= $carouselEbook->CoverImageAvifUrl ?> 1x" type="image/avif"><? } ?>
 							<source srcset="<?= $carouselEbook->CoverImage2xUrl ?> 2x, <?= $carouselEbook->CoverImageUrl ?> 1x" type="image/jpg">
 							<img src="<?= $carouselEbook->HeroImage2xUrl ?>" alt="The cover for the Standard Ebooks edition of <?= Formatter::ToPlainText(strip_tags($carouselEbook->TitleWithCreditsHtml)) ?>">
 						</picture>