diff --git a/test/tests/zoteroPaneTest.js b/test/tests/zoteroPaneTest.js
index 372484032b..63353cdca5 100644
--- a/test/tests/zoteroPaneTest.js
+++ b/test/tests/zoteroPaneTest.js
@@ -1686,6 +1686,38 @@ describe("ZoteroPane", function () {
 		});
 
 		it("should shift-tab across the zotero pane", async function () {
+			// TEMP: List open windows to diagnose the intermittent timeout
+			let describeWindows = function () {
+				let lines = [];
+				for (let openWin of Services.wm.getEnumerator(null)) {
+					lines.push("type=" + (openWin.document.documentElement.getAttribute("windowtype") || "")
+						+ ", URL=" + openWin.location.href
+						+ ", title=" + JSON.stringify(openWin.document.title)
+						+ ", active=" + (openWin === Services.focus.activeWindow));
+				}
+				return lines.length ? "\n  " + lines.join("\n  ") : " (none)";
+			};
+			let windowsAtStart = describeWindows();
+			// Surface the open-window list in the failure message. On a plain
+			// hang Mocha just reports a context-free 15s timeout and none of our
+			// code runs, so wrap each await to reject with the window list instead.
+			// Done this way rather than logging at the start via Zotero.Debug.init(),
+			// which enables app-wide debug output that adds latency into the focus
+			// race and could keep the intermittent failure from reproducing.
+			let withTimeout = function (promise, label) {
+				let timer;
+				let timeout = new Promise(function (resolve, reject) {
+					timer = setTimeout(function () {
+						reject(new Error("Timed out waiting for " + label
+							+ "\nActive element: "
+							+ (doc.activeElement.id || [...doc.activeElement.classList].join("."))
+							+ "\nOpen windows at start:" + windowsAtStart
+							+ "\nOpen windows now:" + describeWindows()));
+					}, 5000);
+				});
+				return Promise.race([promise, timeout]).finally(() => clearTimeout(timer));
+			};
+
 			// Start from the Advanced Search button (the last focusable element in the
 			// search field) so the first shift-tab exercises advanced button -> search field
 			let advancedButton = doc.getElementById('zotero-tb-search-advanced-button');
@@ -1713,10 +1745,10 @@ describe("ZoteroPane", function () {
 				}
 				doc.activeElement.dispatchEvent(shiftTab);
 				if (focusPromise) {
-					await focusPromise;
+					await withTimeout(focusPromise, "focusin on " + id);
 				}
 				if (hidePromise) {
-					await hidePromise;
+					await withTimeout(hidePromise, "collections-search to hide before " + id);
 				}
 				// Some elements don't have id, so use classes to verify they're focused
 				if (doc.activeElement.id) {