diff --git a/toolkit/components/satchel/nsFormAutoComplete.js b/toolkit/components/satchel/nsFormAutoComplete.js
index d67806d6d52..b858bff296b 100644
--- a/toolkit/components/satchel/nsFormAutoComplete.js
+++ b/toolkit/components/satchel/nsFormAutoComplete.js
@@ -216,21 +216,21 @@ FormAutoComplete.prototype = {
             // of results in wrappedResult._values and only the results from
             // form history in wrappedResults.entries.
             // First, grab the entire list of old results.
-            let allResults = wrappedResult._values;
+            let allResults = wrappedResult._labels;
             let datalistResults, datalistLabels;
             if (allResults) {
                 // We have datalist results, extract them from the values array.
-                datalistResults = allResults.slice(wrappedResult.entries.length);
+                datalistLabels = allResults.slice(wrappedResult.entries.length);
                 let filtered = [];
-                datalistLabels = [];
-                for (let i = datalistResults.length; i > 0; --i) {
-                    if (datalistResults[i - 1].contains(searchString)) {
-                        filtered.push(datalistResults[i - 1]);
-                        datalistLabels.push(wrappedResult._labels[i - 1]);
+                datalistResults = [];
+                for (let i = 0; i < datalistLabels.length; ++i) {
+                    if (datalistLabels[i].toLowerCase().includes(searchString)) {
+                        filtered.push(datalistLabels[i]);
+                        datalistResults.push(wrappedResult._values[i]);
                     }
                 }
 
-                datalistResults = filtered;
+                datalistLabels = filtered;
             }
 
             let searchTokens = searchString.split(/\s+/);
diff --git a/toolkit/components/satchel/test/test_form_autocomplete_with_list.html b/toolkit/components/satchel/test/test_form_autocomplete_with_list.html
index 1cb35e04efa..e206c2135f4 100644
--- a/toolkit/components/satchel/test/test_form_autocomplete_with_list.html
+++ b/toolkit/components/satchel/test/test_form_autocomplete_with_list.html
@@ -203,6 +203,28 @@ function runTest() {
         doKey("return");
         checkForm("Google");
 
+        expectPopup();
+        restoreForm();
+        doKey("down");
+        break;
+
+    case 10:
+        // Test autocompletion of datalists with cached results.
+        sendString("PAS");
+        waitForMenuChange(2);
+        break;
+
+    case 11:
+        // Continuation of test 10
+        sendString("S1");
+        waitForMenuChange(1);
+        break;
+
+    case 12:
+        doKey("down");
+        doKey("return");
+        checkForm("Google");
+
         // Trigger autocomplete popup
         // Look at form 3, try to trigger autocomplete popup
         input.value = "";