diff --git a/toolkit/components/passwordmgr/test/mochitest/pwmgr_common.js b/toolkit/components/passwordmgr/test/mochitest/pwmgr_common.js
index 144776cb2773..04eb22558e39 100644
--- a/toolkit/components/passwordmgr/test/mochitest/pwmgr_common.js
+++ b/toolkit/components/passwordmgr/test/mochitest/pwmgr_common.js
@@ -76,24 +76,28 @@ function recreateTree(element) {
  * *labels* are being shown correctly as items in the popup.
  */
 function checkAutoCompleteResults(actualValues, expectedValues, hostname, msg) {
-  if (hostname !== null) {
-    isnot(
-      actualValues.length,
-      0,
-      "There should be items in the autocomplete popup: " +
-        JSON.stringify(actualValues)
-    );
-
-    // Check the footer first.
-    let footerResult = actualValues[actualValues.length - 1];
-    is(footerResult, "View Saved Logins", "the footer text is shown correctly");
-  }
-
   if (hostname === null) {
     checkArrayValues(actualValues, expectedValues, msg);
     return;
   }
 
+  is(
+    typeof hostname,
+    "string",
+    "checkAutoCompleteResults: hostname must be a string"
+  );
+
+  isnot(
+    actualValues.length,
+    0,
+    "There should be items in the autocomplete popup: " +
+      JSON.stringify(actualValues)
+  );
+
+  // Check the footer first.
+  let footerResult = actualValues[actualValues.length - 1];
+  is(footerResult, "View Saved Logins", "the footer text is shown correctly");
+
   if (actualValues.length == 1) {
     is(
       expectedValues.length,
diff --git a/toolkit/components/passwordmgr/test/mochitest/test_autocomplete_https_downgrade.html b/toolkit/components/passwordmgr/test/mochitest/test_autocomplete_https_downgrade.html
index f6b11cfdcdc6..bc9e79ff0e8d 100644
--- a/toolkit/components/passwordmgr/test/mochitest/test_autocomplete_https_downgrade.html
+++ b/toolkit/components/passwordmgr/test/mochitest/test_autocomplete_https_downgrade.html
@@ -83,7 +83,7 @@ async function setup(formUrl) {
 
   await promiseFormsProcessed();
 
-  hostname = SpecialPowers.spawn(getIframeBrowsingContext(window), [], function() {
+  hostname = await SpecialPowers.spawn(getIframeBrowsingContext(window), [], function() {
     return this.content.document.documentURIObject.host;
   });
 }
diff --git a/toolkit/components/passwordmgr/test/mochitest/test_autocomplete_https_upgrade.html b/toolkit/components/passwordmgr/test/mochitest/test_autocomplete_https_upgrade.html
index 91d14a33412f..79999dbe2da5 100644
--- a/toolkit/components/passwordmgr/test/mochitest/test_autocomplete_https_upgrade.html
+++ b/toolkit/components/passwordmgr/test/mochitest/test_autocomplete_https_upgrade.html
@@ -81,7 +81,7 @@ async function setup(formUrl = HTTPS_FORM_URL) {
 
   await promiseFormsProcessed();
 
-  hostname = SpecialPowers.spawn(getIframeBrowsingContext(window), [], function() {
+  hostname = await SpecialPowers.spawn(getIframeBrowsingContext(window), [], function() {
     return this.content.document.documentURIObject.host;
   });
 }
diff --git a/toolkit/components/passwordmgr/test/mochitest/test_autofocus_js.html b/toolkit/components/passwordmgr/test/mochitest/test_autofocus_js.html
index df661a0dff9b..856bde1411ac 100644
--- a/toolkit/components/passwordmgr/test/mochitest/test_autofocus_js.html
+++ b/toolkit/components/passwordmgr/test/mochitest/test_autofocus_js.html
@@ -60,7 +60,7 @@ add_task(async function setup() {
 
   await promiseFormsProcessed();
 
-  hostname = SpecialPowers.spawn(getIframeBrowsingContext(window), [], function() {
+  hostname = await SpecialPowers.spawn(getIframeBrowsingContext(window), [], function() {
     return this.content.document.documentURIObject.host;
   });