diff --git a/source/java/org/alfresco/web/bean/CheckinCheckoutBean.java b/source/java/org/alfresco/web/bean/CheckinCheckoutBean.java
index 4e8679ed3..13e9d5bab 100644
--- a/source/java/org/alfresco/web/bean/CheckinCheckoutBean.java
+++ b/source/java/org/alfresco/web/bean/CheckinCheckoutBean.java
@@ -831,7 +831,8 @@ public class CheckinCheckoutBean
       {
          try
          {
-            tx = Repository.getUserTransaction(FacesContext.getCurrentInstance());
+            FacesContext context = FacesContext.getCurrentInstance();
+            tx = Repository.getUserTransaction(context);
             tx.begin();
             
             if (logger.isDebugEnabled())
@@ -839,7 +840,12 @@ public class CheckinCheckoutBean
             
             // get an updating writer that we can use to modify the content on the current node
             ContentWriter writer = this.contentService.getWriter(node.getNodeRef(), ContentModel.PROP_CONTENT, true);
-            writer.putContent(this.file);
+            
+            // also update the mime type in case a different type of file is uploaded
+            String mimeType = Repository.getMimeTypeForFileName(context, this.fileName);
+            writer.setMimetype(mimeType);
+            
+            writer.putContent(this.file);            
             
             // commit the transaction
             tx.commit();