diff --git a/installer/data/mysql/atomicupdate/bug_26638_ArticleRequestsMandatoryFieldsItemsOnly.perl b/installer/data/mysql/atomicupdate/bug_26638_ArticleRequestsMandatoryFieldsItemsOnly.perl
new file mode 100644
index 0000000000..d95cf12e30
--- /dev/null
+++ b/installer/data/mysql/atomicupdate/bug_26638_ArticleRequestsMandatoryFieldsItemsOnly.perl
@@ -0,0 +1,11 @@
+$DBversion = 'XXX'; # will be replaced by the RM
+if( CheckVersion( $DBversion ) ) {
+    $dbh->do(q{
+        INSERT IGNORE INTO `systempreferences` (`variable`, `value`, `options`, `explanation`, `type`) VALUES
+            ('ArticleRequestsMandatoryFieldsItemOnly', '', NULL, 'Comma delimited list of required fields for bibs where article requests rule = ''item_only''', 'multiple')
+    });
+    $dbh->do(q{
+        DELETE FROM systempreferences WHERE variable = "ArticleRequestsMandatoryFieldsItemsOnly"
+    });
+    NewVersion( $DBversion, 26638, "Add missing system preference ArticleRequestsMandatoryFieldsItemOnly");
+}
diff --git a/installer/data/mysql/mandatory/sysprefs.sql b/installer/data/mysql/mandatory/sysprefs.sql
index ead0185099..a6f27e5e7f 100644
--- a/installer/data/mysql/mandatory/sysprefs.sql
+++ b/installer/data/mysql/mandatory/sysprefs.sql
@@ -57,7 +57,7 @@ INSERT INTO systempreferences ( `variable`, `value`, `options`, `explanation`, `
 ('ArticleRequests', '0', NULL, 'Enables the article request feature', 'YesNo'),
 ('ArticleRequestsLinkControl', 'calc', 'always|calc', 'Control display of article request link on search results', 'Choice'),
 ('ArticleRequestsMandatoryFields', '', NULL, 'Comma delimited list of required fields for bibs where article requests rule = ''yes''', 'multiple'),
-('ArticleRequestsMandatoryFieldsItemsOnly', '', NULL, 'Comma delimited list of required fields for bibs where article requests rule = ''item_only''', 'multiple'),
+('ArticleRequestsMandatoryFieldsItemOnly', '', NULL, 'Comma delimited list of required fields for bibs where article requests rule = ''item_only''', 'multiple'),
 ('ArticleRequestsMandatoryFieldsRecordOnly', '', NULL, 'Comma delimited list of required fields for bibs where article requests rule = ''bib_only''', 'multiple'),
 ('AudioAlerts','0','','Enable circulation sounds during checkin and checkout in the staff interface.  Not supported by all web browsers yet.','YesNo'),
 ('AuthDisplayHierarchy','0','','Display authority hierarchies','YesNo'),