diff --git a/assets/js/autocomplete.ts b/assets/js/autocomplete.ts
index aceb13f4..31939ead 100644
--- a/assets/js/autocomplete.ts
+++ b/assets/js/autocomplete.ts
@@ -9,7 +9,9 @@ import { TermContext } from './query/lex';
 import { $$ } from './utils/dom';
 import { fetchLocalAutocomplete, fetchSuggestions, SuggestionsPopup, TermSuggestion } from './utils/suggestions';
 
-let inputField: HTMLInputElement | null = null,
+type InputFieldElement = HTMLInputElement | HTMLTextAreaElement;
+
+let inputField: InputFieldElement | null = null,
   originalTerm: string | undefined,
   originalQuery: string | undefined,
   selectedTerm: TermContext | null = null;
@@ -105,19 +107,36 @@ function keydownHandler(event: KeyboardEvent) {
   }
 }
 
-function findSelectedTerm(targetInput: HTMLInputElement, searchQuery: string): TermContext | null {
+function findSelectedTerm(targetInput: InputFieldElement, searchQuery: string): TermContext | null {
   if (targetInput.selectionStart === null || targetInput.selectionEnd === null) return null;
 
   const selectionIndex = Math.min(targetInput.selectionStart, targetInput.selectionEnd);
-  const terms = getTermContexts(searchQuery);
 
-  return terms.find(([range]) => range[0] < selectionIndex && range[1] >= selectionIndex) ?? null;
+  // Multi-line textarea elements should treat each line as the different search queries. Here we're looking for the
+  // actively edited line and use it instead of the whole value.
+  const activeLineStart = searchQuery.slice(0, selectionIndex).lastIndexOf('\n') + 1;
+  const lengthAfterSelectionIndex = Math.max(searchQuery.slice(selectionIndex).indexOf('\n'), 0);
+  const targetQuery = searchQuery.slice(activeLineStart, selectionIndex + lengthAfterSelectionIndex);
+
+  const terms = getTermContexts(targetQuery);
+  const searchIndex = selectionIndex - activeLineStart;
+  const term = terms.find(([range]) => range[0] < searchIndex && range[1] >= searchIndex) ?? null;
+
+  // Converting line-specific indexes back to absolute ones.
+  if (term) {
+    const [range] = term;
+
+    range[0] += activeLineStart;
+    range[1] += activeLineStart;
+  }
+
+  return term;
 }
 
 function toggleSearchAutocomplete() {
   const enable = store.get('enable_search_ac');
 
-  for (const searchField of $$<HTMLInputElement>('input[data-ac-mode=search]')) {
+  for (const searchField of $$<InputFieldElement>(':is(input, textarea)[data-ac-mode=search]')) {
     if (enable) {
       searchField.autocomplete = 'off';
     } else {
@@ -144,13 +163,13 @@ function listenAutocomplete() {
     loadAutocompleteFromEvent(event);
     window.clearTimeout(serverSideSuggestionsTimeout);
 
-    if (!(event.target instanceof HTMLInputElement)) return;
+    if (!(event.target instanceof HTMLInputElement) && !(event.target instanceof HTMLTextAreaElement)) return;
 
     const targetedInput = event.target;
 
     if (!targetedInput.dataset.ac) return;
 
-    targetedInput.addEventListener('keydown', keydownHandler);
+    targetedInput.addEventListener('keydown', keydownHandler as EventListener);
 
     if (localAc !== null) {
       inputField = targetedInput;
@@ -212,7 +231,7 @@ function listenAutocomplete() {
   });
 
   function loadAutocompleteFromEvent(event: Event) {
-    if (!(event.target instanceof HTMLInputElement)) return;
+    if (!(event.target instanceof HTMLInputElement) && !(event.target instanceof HTMLTextAreaElement)) return;
 
     if (!isLocalLoading && event.target.dataset.ac) {
       isLocalLoading = true;
diff --git a/lib/philomena_web/templates/filter/_form.html.slime b/lib/philomena_web/templates/filter/_form.html.slime
index e46cda9a..2482f71f 100644
--- a/lib/philomena_web/templates/filter/_form.html.slime
+++ b/lib/philomena_web/templates/filter/_form.html.slime
@@ -26,7 +26,7 @@
     .field
       = label f, :spoilered_complex_str, "Complex Spoiler Filter"
       br
-      = textarea f, :spoilered_complex_str, class: "input input--wide",  autocapitalize: "none"
+      = textarea f, :spoilered_complex_str, class: "input input--wide",  autocapitalize: "none", data: [ac: "true", ac_min_length: 3, ac_mode: "search"]
       br
       = error_tag f, :spoilered_complex_str
     .fieldlabel
@@ -51,7 +51,7 @@
     .field
       = label f, :hidden_complex_str, "Complex Hide Filter"
       br
-      = textarea f, :hidden_complex_str, class: "input input--wide",  autocapitalize: "none"
+      = textarea f, :hidden_complex_str, class: "input input--wide",  autocapitalize: "none", data: [ac: "true", ac_min_length: 3, ac_mode: "search"]
       br
       = error_tag f, :hidden_complex_str
     .fieldlabel