diff --git a/.changeset/khaki-needles-hope.md b/.changeset/khaki-needles-hope.md
new file mode 100644
index 0000000000..0e4160bfb6
--- /dev/null
+++ b/.changeset/khaki-needles-hope.md
@@ -0,0 +1,5 @@
+---
+'mermaid': patch
+---
+
+Marked `mermaid` as free of side-effects for improved tree shaking
diff --git a/packages/mermaid/package.json b/packages/mermaid/package.json
index 2469af2ff8..b2099a8d2b 100644
--- a/packages/mermaid/package.json
+++ b/packages/mermaid/package.json
@@ -5,6 +5,7 @@
   "type": "module",
   "module": "./dist/mermaid.core.mjs",
   "types": "./dist/mermaid.d.ts",
+  "sideEffects": false,
   "exports": {
     ".": {
       "types": "./dist/mermaid.d.ts",