diff --git a/scm/plugin.jelly b/scm/plugin.jelly
index 56e9b39b..d65df49a 100644
--- a/scm/plugin.jelly
+++ b/scm/plugin.jelly
@@ -320,12 +320,20 @@
     <!-- TODO: verify that the name is valid for a tag -->
 
     <!-- Update project.xml -->
+    <j:set var="pomFilename" value="project.xml" />
+    <util:file var="file" name="${pomFilename}"/>
+    <j:if test="${!file.canWrite()}">
+      <ant:fail>project.xml is not writable!</ant:fail>
+    </j:if>
     <t:release-version version="${version_name}" tag="${tag_name}" />
 
     <!-- Update changes.xml if it exists -->
     <j:set var="changesFilename" value="${maven.docs.src}/changes.xml" />
     <util:file var="file" name="${changesFilename}"/>
     <j:if test="${file.exists()}">
+      <j:if test="${!file.canWrite()}">
+        <ant:fail>changes.xml exists but is not writable!</ant:fail>
+      </j:if>
       <c:release-version version="${version_name}" />
     </j:if>
 
diff --git a/scm/xdocs/changes.xml b/scm/xdocs/changes.xml
index be21aabd..c7d0bde8 100644
--- a/scm/xdocs/changes.xml
+++ b/scm/xdocs/changes.xml
@@ -24,6 +24,7 @@
   </properties>
   <body>
     <release version="1.6.1-SNAPSHOT" date="In SVN">
+      <action dev="ltheussl" type="fix" issue="MPSCM-63">The prepare-release goal should fail if project.xml can't be edited (e.g. read only).</action>
       <action dev="ltheussl" type="fix" issue="MPSCM-89">SCM Parse Connection output is wrong / misleading.</action>
       <action dev="ltheussl" type="fix" issue="MPSCM-86">scm:prepare-release does not commit modified changes.xml.</action>
       <action dev="ltheussl" type="update">Update dom4j and jelly dependencies to match the ones in maven 1.1 core.</action>
