diff --git a/data/local_vulnerable_files.xml b/data/local_vulnerable_files.xml
index d8dbd0a7..03e2b241 100644
--- a/data/local_vulnerable_files.xml
+++ b/data/local_vulnerable_files.xml
@@ -54,13 +54,13 @@
   <hash sha1="ac638cc38f011b74a8d9a4e7d3d60358e472166c">
     <title>Inline phpinfo()</title>
     <file>phpinfo.php</file>
-    <reference></reference>
+    <reference>http://php.net/manual/en/function.phpinfo.php</reference>
   </hash>
 
   <hash sha1="012ee25cceff745e681fbb3697a06f3712f55554">
     <title>phpinfo()</title>
     <file>phpinfo.php</file>
-    <reference></reference>
+    <reference>http://php.net/manual/en/function.phpinfo.php</reference>
   </hash>
 
 </hashes>
diff --git a/data/local_vulnerable_files.xsd b/data/local_vulnerable_files.xsd
index c5074cf5..5ce8ff6d 100644
--- a/data/local_vulnerable_files.xsd
+++ b/data/local_vulnerable_files.xsd
@@ -21,11 +21,15 @@
 <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
 
   <xs:simpleType name="stringtype">
-    <xs:restriction base="xs:string"/>
+    <xs:restriction base="xs:string">
+      <xs:minLength value="1" />
+    </xs:restriction>
   </xs:simpleType>
 
   <xs:simpleType name="uritype">
-    <xs:restriction base="xs:anyURI"/>
+    <xs:restriction base="xs:anyURI">
+      <xs:minLength value="1" />
+    </xs:restriction>
   </xs:simpleType>
 
   <xs:simpleType name="sha1type">
diff --git a/data/vuln.xsd b/data/vuln.xsd
index aee74e38..0a46b9f7 100644
--- a/data/vuln.xsd
+++ b/data/vuln.xsd
@@ -21,15 +21,19 @@
 <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
 
   <xs:simpleType name="stringtype">
-    <xs:restriction base="xs:string"/>
+    <xs:restriction base="xs:string">
+      <xs:minLength value="1" />
+    </xs:restriction>
   </xs:simpleType>
 
   <xs:simpleType name="uritype">
-    <xs:restriction base="xs:anyURI"/>
+    <xs:restriction base="xs:anyURI">
+      <xs:minLength value="1" />
+    </xs:restriction>
   </xs:simpleType>
 
   <xs:simpleType name="typetype">
-    <xs:restriction base="xs:string">
+    <xs:restriction base="stringtype">
       <xs:enumeration value="SQLI"/>
       <xs:enumeration value="MULTI"/>
       <xs:enumeration value="REDIRECT"/>
diff --git a/data/wp_versions.xsd b/data/wp_versions.xsd
index 53e8c114..80f70726 100644
--- a/data/wp_versions.xsd
+++ b/data/wp_versions.xsd
@@ -21,7 +21,9 @@
 <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
 
   <xs:simpleType name="stringtype">
-    <xs:restriction base="xs:string"/>
+    <xs:restriction base="xs:string">
+      <xs:minLength value="1" />
+    </xs:restriction>
   </xs:simpleType>
 
   <xs:complexType name="filetype">