diff --git a/.changeset/silver-jokes-tease.md b/.changeset/silver-jokes-tease.md
new file mode 100644
index 00000000..c9b39f4f
--- /dev/null
+++ b/.changeset/silver-jokes-tease.md
@@ -0,0 +1,5 @@
+---
+'@remote-dom/polyfill': minor
+---
+
+Fix trying to write to readonly events
diff --git a/packages/polyfill/source/Event.ts b/packages/polyfill/source/Event.ts
index 0b2390d8..1dfe5508 100644
--- a/packages/polyfill/source/Event.ts
+++ b/packages/polyfill/source/Event.ts
@@ -117,9 +117,22 @@ export function fireEvent(
   if (!list) return;
 
   for (const listener of list) {
-    event.eventPhase =
-      event.target === currentTarget ? EventPhase.AT_TARGET : phase;
-    event.currentTarget = currentTarget;
+    // Safely set eventPhase property only if it's writable
+    try {
+      event.eventPhase =
+        event.target === currentTarget ? EventPhase.AT_TARGET : phase;
+    } catch {
+      // eventPhase property is read-only on native DOM Events
+      // Event will still function but may have different phase behavior
+    }
+
+    // Safely set currentTarget property only if it's writable
+    try {
+      event.currentTarget = currentTarget;
+    } catch {
+      // currentTarget property is read-only on native DOM Events
+      // Event will still function but currentTarget may not update correctly during bubbling
+    }
 
     try {
       if (typeof listener === 'object') {
diff --git a/packages/polyfill/source/EventTarget.ts b/packages/polyfill/source/EventTarget.ts
index ea448660..08528fd8 100644
--- a/packages/polyfill/source/EventTarget.ts
+++ b/packages/polyfill/source/EventTarget.ts
@@ -109,8 +109,19 @@ export class EventTarget {
     // while (target instanceof Node && (target = target.parentNode)) {
     //   path.push(target);
     // }
-    event.target = this;
-    event.srcElement = this;
+    // Safely set target property only if it's writable (native DOM Events have read-only target)
+    try {
+      event.target = this;
+    } catch {
+      // target property is read-only on native DOM Events
+      // Event will still function but may have different target than expected
+    }
+
+    try {
+      event.srcElement = this;
+    } catch {
+      // srcElement property may also be read-only on some implementations
+    }
     event[PATH] = path;
 
     for (let i = path.length; i--; ) {