diff --git a/app/components/primer/alpha/dialog.pcss b/app/components/primer/alpha/dialog.pcss
index 6c9cef048b..e5fed4ca8c 100644
--- a/app/components/primer/alpha/dialog.pcss
+++ b/app/components/primer/alpha/dialog.pcss
@@ -8,6 +8,12 @@
 
 /* Overlay */
 
+@property --dialog-scrollgutter {
+  initial-value: 0;
+  inherits: false;
+  syntax: "<length>";
+}
+
 /* TODO: One day this can be :has(:modal), when it is better supported */
 body.has-modal {
   padding-right: var(--dialog-scrollgutter) !important;
diff --git a/app/components/primer/dialog_helper.ts b/app/components/primer/dialog_helper.ts
index e0ff666d83..99561223f2 100644
--- a/app/components/primer/dialog_helper.ts
+++ b/app/components/primer/dialog_helper.ts
@@ -1,4 +1,12 @@
+let dialogScrollGutterSet = false
 function dialogInvokerButtonHandler(event: Event) {
+  if (!dialogScrollGutterSet) {
+    this.ownerDocument.body.style.setProperty(
+      '--dialog-scrollgutter',
+      `${window.innerWidth - this.ownerDocument.body.clientWidth}px`,
+    )
+    dialogScrollGutterSet = true;
+  }
   const target = event.target as HTMLElement
   const button = target?.closest('button')
 
@@ -76,10 +84,6 @@ export class DialogHelperElement extends HTMLElement {
     const {signal} = (this.#abortController = new AbortController())
     document.addEventListener('click', dialogInvokerButtonHandler, true)
     document.addEventListener('click', this, {signal})
-    this.ownerDocument.body.style.setProperty(
-      '--dialog-scrollgutter',
-      `${window.innerWidth - this.ownerDocument.body.clientWidth}px`,
-    )
     new MutationObserver(records => {
       for (const record of records) {
         if (record.target === this.dialog) {