From ea4843c5ad6f37d2b480e55cdd9f9f27797d119e Mon Sep 17 00:00:00 2001
From: Simon H <5968653+dummdidumm@users.noreply.github.com>
Date: Wed, 16 Apr 2025 21:24:04 +0200
Subject: [PATCH] fix: avoid unnecessary read version increments (#15777)

Fixes #15262
---
 .changeset/sweet-adults-complain.md            | 5 +++++
 packages/svelte/src/internal/client/runtime.js | 2 +-
 2 files changed, 6 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/sweet-adults-complain.md

diff --git a/.changeset/sweet-adults-complain.md b/.changeset/sweet-adults-complain.md
new file mode 100644
index 0000000000..429b034b3d
--- /dev/null
+++ b/.changeset/sweet-adults-complain.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: avoid unnecessary read version increments
diff --git a/packages/svelte/src/internal/client/runtime.js b/packages/svelte/src/internal/client/runtime.js
index 2acad3d258..e621536055 100644
--- a/packages/svelte/src/internal/client/runtime.js
+++ b/packages/svelte/src/internal/client/runtime.js
@@ -469,7 +469,7 @@ export function update_reaction(reaction) {
 		// we need to increment the read version to ensure that
 		// any dependencies in this reaction aren't marked with
 		// the same version
-		if (previous_reaction !== reaction) {
+		if (previous_reaction !== null && previous_reaction !== reaction) {
 			read_version++;
 
 			if (untracked_writes !== null) {