diff --git a/lib/galaxy/tool_util/xsd/galaxy.xsd b/lib/galaxy/tool_util/xsd/galaxy.xsd
index a045909d140..461600fa68b 100644
--- a/lib/galaxy/tool_util/xsd/galaxy.xsd
+++ b/lib/galaxy/tool_util/xsd/galaxy.xsd
@@ -4449,6 +4449,7 @@ used to generate dynamic options.
       <xs:element name="filter" type="Filter" minOccurs="0" maxOccurs="unbounded"/>
       <xs:element name="column" type="Column" minOccurs="0" maxOccurs="unbounded"/>
       <xs:element name="validator" type="Validator" minOccurs="0" maxOccurs="1"/>
+      <xs:element name="postprocess_expression" type="Expression" minOccurs="0" maxOccurs="1"/>
       <xs:element name="file" type="xs:string" minOccurs="0" maxOccurs="unbounded">
         <xs:annotation>
           <xs:documentation xml:lang="en">Documentation for file</xs:documentation>
diff --git a/test/functional/tools/select_from_url.xml b/test/functional/tools/select_from_url.xml
index 69cb50166d5..30567392419 100644
--- a/test/functional/tools/select_from_url.xml
+++ b/test/functional/tools/select_from_url.xml
@@ -16,7 +16,7 @@ echo '$url_param_value_postprocessed' > '$param_value_postprocessed'
         -->
         <param name="url_param_value_postprocessed" type="select">
             <options from_url="https://usegalaxy.org/api/genomes/dm6">
-                <postprocess_expression><![CDATA[
+                <postprocess_expression type="ecma5.1"><![CDATA[
                     $( Object.values(inputs.chrom_info).map((v) => [v.chrom, v.len]) )
                 ]]></postprocess_expression>
             </options>