diff --git a/PDF_A/PDFA-4.xml b/PDF_A/PDFA-4.xml
index 1b40dcba..3c7abe4c 100644
--- a/PDF_A/PDFA-4.xml
+++ b/PDF_A/PDFA-4.xml
@@ -1187,7 +1187,7 @@
             <description>The value of "pdfaid:rev" shall be the four digit year</description>
             <test>/^\d{4}$/.test(rev)</test>
             <error>
-                <message>The value of "pdfaid:rev" (%1) not the four digit year</message>
+                <message>The value of "pdfaid:rev" (%1) is not the four digit year</message>
                 <arguments>
                     <argument>rev</argument>
                 </arguments>
diff --git a/PDF_A/PDFA-4E.xml b/PDF_A/PDFA-4E.xml
index 73a32682..411f7fd1 100644
--- a/PDF_A/PDFA-4E.xml
+++ b/PDF_A/PDFA-4E.xml
@@ -1203,7 +1203,7 @@
             <description>The value of "pdfaid:rev" shall be the four digit year</description>
             <test>/^\d{4}$/.test(rev)</test>
             <error>
-                <message>The value of "pdfaid:rev" (%1) not the four digit year</message>
+                <message>The value of "pdfaid:rev" (%1) is not the four digit year</message>
                 <arguments>
                     <argument>rev</argument>
                 </arguments>
diff --git a/PDF_A/PDFA-4F.xml b/PDF_A/PDFA-4F.xml
index f9a4ddff..b40fba90 100644
--- a/PDF_A/PDFA-4F.xml
+++ b/PDF_A/PDFA-4F.xml
@@ -1189,7 +1189,7 @@
             <description>The value of "pdfaid:rev" shall be the four digit year</description>
             <test>/^\d{4}$/.test(rev)</test>
             <error>
-                <message>The value of "pdfaid:rev" (%1) not the four digit year</message>
+                <message>The value of "pdfaid:rev" (%1) is not the four digit year</message>
                 <arguments>
                     <argument>rev</argument>
                 </arguments>