From 43d693c3089dd8f0fe7b46618f5555d43c936cad Mon Sep 17 00:00:00 2001
From: Juraj Kapsz <github@jurajkapsz.sk>
Date: Mon, 15 Apr 2024 10:52:39 +0200
Subject: [PATCH] fix: picture fallback check (#10783)

---
 .changeset/modern-mugs-raise.md         | 5 +++++
 packages/astro/components/Picture.astro | 2 +-
 2 files changed, 6 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/modern-mugs-raise.md

diff --git a/.changeset/modern-mugs-raise.md b/.changeset/modern-mugs-raise.md
new file mode 100644
index 000000000000..0796acf9f8eb
--- /dev/null
+++ b/.changeset/modern-mugs-raise.md
@@ -0,0 +1,5 @@
+---
+"astro": patch
+---
+
+Fixes Picture component specialFormatsFallback fallback check
diff --git a/packages/astro/components/Picture.astro b/packages/astro/components/Picture.astro
index f23ab6ccce7a..6dcc50c8e1d6 100644
--- a/packages/astro/components/Picture.astro
+++ b/packages/astro/components/Picture.astro
@@ -45,7 +45,7 @@ let resultFallbackFormat = fallbackFormat ?? defaultFallbackFormat;
 if (
 	!fallbackFormat &&
 	isESMImportedImage(originalSrc) &&
-	originalSrc.format in specialFormatsFallback
+	(specialFormatsFallback as ReadonlyArray<string>).includes(originalSrc.format)
 ) {
 	resultFallbackFormat = originalSrc.format;
 }