diff --git a/config/locales/en.yml b/config/locales/en.yml
index 491ca5cef..fcc2d813a 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -492,8 +492,8 @@ en:
   sign_this_request: 'Sign this request'
   revoke_this_certificate: 'Revoke this certificate'
   crt_revoked: 'CRT (revoked)'
-  contact_org_error: 'Parameter value policy error. Org should be blank'
-  contact_fax_error: 'Parameter value policy error. Fax should be blank'
+  contact_org_error: 'Parameter value policy error. Org must be blank'
+  contact_fax_error: 'Parameter value policy error. Fax must be blank'
   invoices: 'Invoices'
   no_such_user: 'No such user'
   log_in: 'Log in'
diff --git a/doc/epp-examples.md b/doc/epp-examples.md
index cb6433d1d..c68d942d2 100644
--- a/doc/epp-examples.md
+++ b/doc/epp-examples.md
@@ -547,7 +547,7 @@ RESPONSE:
 <epp schemaLocation="urn:ietf:params:xml:ns:epp-1.0 epp-1.0.xsd">
   <response>
     <result code="2306">
-      <msg lang="en">Parameter value policy error. Org should be blank: postalInfo &gt; org [org]</msg>
+      <msg lang="en">Parameter value policy error. Org must be blank: postalInfo &gt; org [org]</msg>
     </result>
   </response>
 <trID>
@@ -599,7 +599,7 @@ RESPONSE:
 <epp schemaLocation="urn:ietf:params:xml:ns:epp-1.0 epp-1.0.xsd">
   <response>
     <result code="2306">
-      <msg lang="en">Parameter value policy error. Fax should be blank: fax [fax]</msg>
+      <msg lang="en">Parameter value policy error. Fax must be blank: fax [fax]</msg>
     </result>
   </response>
 <trID>
@@ -1138,7 +1138,7 @@ RESPONSE:
 <epp schemaLocation="urn:ietf:params:xml:ns:epp-1.0 epp-1.0.xsd">
   <response>
     <result code="2306">
-      <msg lang="en">Parameter value policy error. Org should be blank: postalInfo &gt; org [org]</msg>
+      <msg lang="en">Parameter value policy error. Org must be blank: postalInfo &gt; org [org]</msg>
     </result>
   </response>
 <trID>
@@ -1194,7 +1194,7 @@ RESPONSE:
 <epp schemaLocation="urn:ietf:params:xml:ns:epp-1.0 epp-1.0.xsd">
   <response>
     <result code="2306">
-      <msg lang="en">Parameter value policy error. Fax should be blank: fax [fax]</msg>
+      <msg lang="en">Parameter value policy error. Fax must be blank: fax [fax]</msg>
     </result>
   </response>
 <trID>
diff --git a/doc/epp/contact.md b/doc/epp/contact.md
index 164183b3a..a129123f5 100644
--- a/doc/epp/contact.md
+++ b/doc/epp/contact.md
@@ -16,7 +16,7 @@ Contact Mapping protocol short version:
         <contact:id>           0-1      Contact id, optional, generated automatically if missing
         <contact:postalInfo>   1        Postal information container
           <contact:name>       1        Full name of the contact
-          <contact:org>        0        Org is not supported and should be blank or missing
+          <contact:org>        0        Org is not supported and must be blank or missing
           <contact:addr>       1        Address container
             <contact:street>   1-n      Street name
             <contact:city>     1        City name
@@ -50,7 +50,7 @@ Contact Mapping protocol short version:
         <contact:chg>           1        Change container
           <contact:postalInfo>  1        Postal information container
             <contact:name>      0-1      Full name of the contact
-            <contact:org>       0        Org is not supported and should be blank or missing
+            <contact:org>       0        Org is not supported and must be blank or missing
             <contact:addr>      0-1      Address container
               <contact:street>  0-n      Street name
               <contact:city>    0-1      City name
diff --git a/spec/epp/contact_spec.rb b/spec/epp/contact_spec.rb
index 504369d21..ea8bdafa0 100644
--- a/spec/epp/contact_spec.rb
+++ b/spec/epp/contact_spec.rb
@@ -172,7 +172,7 @@ describe 'EPP Contact', epp: true do
       it 'should return parameter value policy error for org' do
         response = create_request({ postalInfo: { org: { value: 'should not save' } } })
         response[:msg].should ==
-          'Parameter value policy error. Org should be blank: postalInfo > org [org]'
+          'Parameter value policy error. Org must be blank: postalInfo > org [org]'
         response[:result_code].should == '2306'
 
         Contact.last.org_name.should == nil
@@ -181,7 +181,7 @@ describe 'EPP Contact', epp: true do
       it 'should return parameter value policy error for fax' do
         response = create_request({ fax: { value: 'should not save' } })
         response[:msg].should ==
-          'Parameter value policy error. Fax should be blank: fax [fax]'
+          'Parameter value policy error. Fax must be blank: fax [fax]'
         response[:result_code].should == '2306'
 
         Contact.last.fax.should == nil
@@ -317,7 +317,7 @@ describe 'EPP Contact', epp: true do
           }
         })
         response[:msg].should ==
-          'Parameter value policy error. Org should be blank: postalInfo > org [org]'
+          'Parameter value policy error. Org must be blank: postalInfo > org [org]'
         response[:result_code].should == '2306'
 
         Contact.find_by(code: 'sh8013').org_name.should == nil
@@ -331,7 +331,7 @@ describe 'EPP Contact', epp: true do
           }
         })
         response[:msg].should ==
-          'Parameter value policy error. Fax should be blank: fax [fax]'
+          'Parameter value policy error. Fax must be blank: fax [fax]'
         response[:result_code].should == '2306'
 
         Contact.find_by(code: 'sh8013').fax.should == nil