diff --git a/koha-tmpl/intranet-tmpl/prog/en/modules/catalogue/advsearch.tt b/koha-tmpl/intranet-tmpl/prog/en/modules/catalogue/advsearch.tt
index f46e93a93c..db8a8f6156 100644
--- a/koha-tmpl/intranet-tmpl/prog/en/modules/catalogue/advsearch.tt
+++ b/koha-tmpl/intranet-tmpl/prog/en/modules/catalogue/advsearch.tt
@@ -114,9 +114,9 @@
 			[% IF ( expanded_options ) %]
             [% IF ( search_box.boolean ) %]
                 <select name="op">
-                    <option value="and" selected="selected">and</option>
-                    <option value="or">or</option>
-                    <option value="not">not</option>
+                    <option value="AND" selected="selected">and</option>
+                    <option value="OR">or</option>
+                    <option value="NOT">not</option>
                 </select>
             [% END %] 
 			[% END %]
diff --git a/koha-tmpl/opac-tmpl/bootstrap/en/modules/opac-advsearch.tt b/koha-tmpl/opac-tmpl/bootstrap/en/modules/opac-advsearch.tt
index b4ac896084..baf8aec28b 100644
--- a/koha-tmpl/opac-tmpl/bootstrap/en/modules/opac-advsearch.tt
+++ b/koha-tmpl/opac-tmpl/bootstrap/en/modules/opac-advsearch.tt
@@ -41,9 +41,9 @@
                                         <div class="search-term-input">
                                             [% IF ( expanded_options ) %]
                                                     <select name="op" class="form-control">
-                                                        <option value="and" selected="selected">and</option>
-                                                        <option value="or">or</option>
-                                                        <option value="not">not</option>
+                                                        <option value="AND" selected="selected">and</option>
+                                                        <option value="OR">or</option>
+                                                        <option value="NOT">not</option>
                                                     </select>
                                             [% ELSE %]
                                                 <label for="search-field_[% loop.index | html %]">