diff --git a/packages/core/signal.mjs b/packages/core/signal.mjs
index 8d410aba..6d903c06 100644
--- a/packages/core/signal.mjs
+++ b/packages/core/signal.mjs
@@ -97,10 +97,12 @@ export const time = signal(id);
  */
 let _mouseY = 0,
   _mouseX = 0;
-document.onmousemove = (e) => {
-  _mouseY = e.clientY / document.body.clientHeight;
-  _mouseX = e.clientX / document.body.clientWidth;
-};
+if (typeof window !== 'undefined') {
+  document.onmousemove = (e) => {
+    _mouseY = e.clientY / document.body.clientHeight;
+    _mouseX = e.clientX / document.body.clientWidth;
+  };
+}
 
 export const mousey = signal(() => _mouseY);
 export const mousex = signal(() => _mouseX);
diff --git a/test/__snapshots__/examples.test.mjs.snap b/test/__snapshots__/examples.test.mjs.snap
index 82d63c4d..0c14000b 100644
--- a/test/__snapshots__/examples.test.mjs.snap
+++ b/test/__snapshots__/examples.test.mjs.snap
@@ -565,6 +565,27 @@ exports[`runs examples > example "_euclidRot" example index 20 1`] = `
 ]
 `;
 
+exports[`runs examples > example "_mouseY" example index 0 1`] = `
+[
+  "[ 0/1 → 1/4 | note:C3 ]",
+  "[ 1/4 → 1/2 | note:C3 ]",
+  "[ 1/2 → 3/4 | note:C3 ]",
+  "[ 3/4 → 1/1 | note:C3 ]",
+  "[ 1/1 → 5/4 | note:C3 ]",
+  "[ 5/4 → 3/2 | note:C3 ]",
+  "[ 3/2 → 7/4 | note:C3 ]",
+  "[ 7/4 → 2/1 | note:C3 ]",
+  "[ 2/1 → 9/4 | note:C3 ]",
+  "[ 9/4 → 5/2 | note:C3 ]",
+  "[ 5/2 → 11/4 | note:C3 ]",
+  "[ 11/4 → 3/1 | note:C3 ]",
+  "[ 3/1 → 13/4 | note:C3 ]",
+  "[ 13/4 → 7/2 | note:C3 ]",
+  "[ 7/2 → 15/4 | note:C3 ]",
+  "[ 15/4 → 4/1 | note:C3 ]",
+]
+`;
+
 exports[`runs examples > example "accelerate" example index 0 1`] = `
 [
   "[ 0/1 → 2/1 | s:sax accelerate:0 ]",