diff --git a/CHANGES.md b/CHANGES.md
index 8f3a739182..4cd26ff896 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -19,6 +19,7 @@
 - #3885: Don't show contact approval alerts when `allow_contact_requests` is false (e.g. anonymous mode)
 - #3886: Don't show OMEMO padlock icon when libsignal is not available (e.g. anonymous mode)
 - #3889: MUC join: Use room jids localpart as name in case name or identity not found
+- #3710: Fix autocomplete adding a trailing space when selecting a group name with the mouse
 - #3916: Add support for XEP-0461 Message Replies, allowing users to reply to specific messages
 - #3939: Don't show invitations to groupchats in which the user is already present
 - #3941: add adhoc completed command result and text-multi as merged lines of text
diff --git a/src/plugins/rosterview/modals/templates/accept-contact-request.js b/src/plugins/rosterview/modals/templates/accept-contact-request.js
index ae0cb3f097..5b3d4d6420 100644
--- a/src/plugins/rosterview/modals/templates/accept-contact-request.js
+++ b/src/plugins/rosterview/modals/templates/accept-contact-request.js
@@ -28,7 +28,7 @@ export default (el) => {
                 <div class="mb-1">
                     <small class="form-text text-muted">${i18n_groups_help}</small>
                 </div>
-                <converse-autocomplete .list=${getGroupsAutoCompleteList()} name="groups"></converse-autocomplete>
+                <converse-autocomplete .list=${getGroupsAutoCompleteList()} name="groups" suffix=""></converse-autocomplete>
             </div>
 
             <div class="mb-3 d-flex justify-content-between">
diff --git a/src/plugins/rosterview/modals/templates/add-contact.js b/src/plugins/rosterview/modals/templates/add-contact.js
index d87fcd47bf..96bec64b5c 100644
--- a/src/plugins/rosterview/modals/templates/add-contact.js
+++ b/src/plugins/rosterview/modals/templates/add-contact.js
@@ -69,7 +69,7 @@ export default (el) => {
                 <div class="mb-1">
                     <small class="form-text text-muted">${i18n_groups_help}</small>
                 </div>
-                <converse-autocomplete .list=${getGroupsAutoCompleteList()} name="groups"></converse-autocomplete>
+                <converse-autocomplete .list=${getGroupsAutoCompleteList()} name="groups" suffix=""></converse-autocomplete>
             </div>
 
             ${el.contact
diff --git a/src/shared/autocomplete/autocomplete.js b/src/shared/autocomplete/autocomplete.js
index 28de20c3dc..e07f433619 100644
--- a/src/shared/autocomplete/autocomplete.js
+++ b/src/shared/autocomplete/autocomplete.js
@@ -22,6 +22,7 @@ export class AutoComplete extends EventEmitter(Object) {
         this.suggestions = [];
         this.is_opened = false;
         this.match_current_word = false; // Match only the current word, otherwise all input is matched
+        this.suffix = ' '; // String to append after the autocompleted value
         this.sort = config.sort === false ? null : SORT_BY_QUERY_POSITION;
         this.filter = FILTER_CONTAINS;
         this.ac_triggers = []; // Array of keys (`ev.key`) values that will trigger auto-complete
@@ -146,7 +147,7 @@ export class AutoComplete extends EventEmitter(Object) {
      */
     insertValue(suggestion) {
         if (this.match_current_word) {
-            u.replaceCurrentWord(this.input, suggestion.value);
+            u.replaceCurrentWord(this.input, suggestion.value, this.suffix);
         } else {
             this.input.value = suggestion.value;
         }
diff --git a/src/shared/autocomplete/component.js b/src/shared/autocomplete/component.js
index 828cbe72ee..271f971152 100644
--- a/src/shared/autocomplete/component.js
+++ b/src/shared/autocomplete/component.js
@@ -66,6 +66,7 @@ export default class AutoCompleteComponent extends CustomElement {
             position: { type: String },
             renderItem: { type: Function },
             required: { type: Boolean },
+            suffix: { type: String },
             triggers: { type: String },
             validate: { type: Function },
             value: { type: String },
@@ -91,6 +92,7 @@ export default class AutoCompleteComponent extends CustomElement {
         this.renderItem = getAutoCompleteItem;
 
         this.required = false;
+        this.suffix = " ";
         this.triggers = "";
         this.validate = null;
         this.value = "";
@@ -143,6 +145,7 @@ export default class AutoCompleteComponent extends CustomElement {
             list: this.list ?? (/** @param {string} q */(q) => this.getAutoCompleteList(q)),
             data: this.data,
             match_current_word: true,
+            suffix: this.suffix,
             max_items: this.max_items,
             min_chars: this.min_chars,
             item: this.renderItem,
diff --git a/src/types/shared/autocomplete/autocomplete.d.ts b/src/types/shared/autocomplete/autocomplete.d.ts
index 2ae3fde3bc..a1c6e2b27b 100644
--- a/src/types/shared/autocomplete/autocomplete.d.ts
+++ b/src/types/shared/autocomplete/autocomplete.d.ts
@@ -21,6 +21,7 @@ export class AutoComplete extends AutoComplete_base {
     suggestions: any[];
     is_opened: boolean;
     match_current_word: boolean;
+    suffix: string;
     sort: (a: any, b: any) => number;
     filter: typeof FILTER_CONTAINS;
     ac_triggers: any[];
diff --git a/src/types/shared/autocomplete/component.d.ts b/src/types/shared/autocomplete/component.d.ts
index 94570553d0..ca76b9b7a2 100644
--- a/src/types/shared/autocomplete/component.d.ts
+++ b/src/types/shared/autocomplete/component.d.ts
@@ -89,6 +89,9 @@ export default class AutoCompleteComponent extends CustomElement {
         required: {
             type: BooleanConstructor;
         };
+        suffix: {
+            type: StringConstructor;
+        };
         triggers: {
             type: StringConstructor;
         };
@@ -115,6 +118,7 @@ export default class AutoCompleteComponent extends CustomElement {
     position: string;
     renderItem: typeof getAutoCompleteItem;
     required: boolean;
+    suffix: string;
     triggers: string;
     validate: any;
     value: string;
diff --git a/src/types/utils/form.d.ts b/src/types/utils/form.d.ts
index 0e5ce70f37..a477c94111 100644
--- a/src/types/utils/form.d.ts
+++ b/src/types/utils/form.d.ts
@@ -30,8 +30,9 @@ export function getCurrentWord(input: HTMLInputElement | HTMLTextAreaElement, in
 /**
  * @param {HTMLInputElement} input - The HTMLElement in which text is being entered
  * @param {string} new_value
+ * @param {string} [suffix=' '] - String to append after the value
  */
-export function replaceCurrentWord(input: HTMLInputElement, new_value: string): void;
+export function replaceCurrentWord(input: HTMLInputElement, new_value: string, suffix?: string): void;
 /**
  * Validates a JID for user input scenarios where locked_domain or default_domain
  * may be configured. When these settings are present, users can enter just a username
diff --git a/src/types/utils/index.d.ts b/src/types/utils/index.d.ts
index 013da0dfd8..19e851015c 100644
--- a/src/types/utils/index.d.ts
+++ b/src/types/utils/index.d.ts
@@ -201,7 +201,7 @@ declare const _default: {
     placeCaretAtEnd(textarea: HTMLTextAreaElement): void;
     isMentionBoundary(s: string): boolean;
     getCurrentWord(input: HTMLInputElement | HTMLTextAreaElement, index?: number, delineator?: string | RegExp): string;
-    replaceCurrentWord(input: HTMLInputElement, new_value: string): void;
+    replaceCurrentWord(input: HTMLInputElement, new_value: string, suffix?: string): void;
     isValidJIDInput(jid: string): boolean;
     isImageWithAlphaChannel(image_file: File): Promise<boolean>;
     compressImage(file: File, options?: import("./types.js").CompressionOptions): Promise<Blob>;
diff --git a/src/utils/form.js b/src/utils/form.js
index f8e7108578..d3d304e5f4 100644
--- a/src/utils/form.js
+++ b/src/utils/form.js
@@ -97,14 +97,15 @@ export function getCurrentWord(input, index, delineator) {
 /**
  * @param {HTMLInputElement} input - The HTMLElement in which text is being entered
  * @param {string} new_value
+ * @param {string} [suffix=' '] - String to append after the value
  */
-export function replaceCurrentWord(input, new_value) {
+export function replaceCurrentWord(input, new_value, suffix = ' ') {
     const caret = input.selectionEnd || undefined;
     const current_word = input.value.slice(0, caret).split(/\s/).pop();
     const value = input.value;
     const mention_boundary = isMentionBoundary(current_word[0]) ? current_word[0] : '';
-    input.value = value.slice(0, caret - current_word.length) + mention_boundary + `${new_value} ` + value.slice(caret);
-    const selection_end = caret - current_word.length + new_value.length + 1;
+    input.value = value.slice(0, caret - current_word.length) + mention_boundary + `${new_value}${suffix}` + value.slice(caret);
+    const selection_end = caret - current_word.length + new_value.length + suffix.length;
     input.selectionEnd = mention_boundary ? selection_end + 1 : selection_end;
 }