diff --git a/hgext/mq.py b/hgext/mq.py
--- a/hgext/mq.py
+++ b/hgext/mq.py
@@ -293,7 +293,10 @@ class patchheader(object):
         if self.comments:
             self._delmsg()
         self.message = [message]
-        self.comments += self.message
+        if message:
+            if self.plainmode and self.comments and self.comments[-1]:
+                self.comments.append('')
+            self.comments.append(message)
 
     def updateheader(self, prefixes, new):
         '''Update all references to a field in the patch header.
diff --git a/tests/test-mq-header-date.t b/tests/test-mq-header-date.t
--- a/tests/test-mq-header-date.t
+++ b/tests/test-mq-header-date.t
@@ -243,6 +243,7 @@
   now at: 1.patch
   ==== qnew -d -m
   Date: 6 0
+  
   Three
   
   1: Three - test - 6.00
@@ -250,6 +251,7 @@
   ==== qref
   adding 3
   Date: 6 0
+  
   Three
   
   diff -r ... 3
@@ -261,6 +263,7 @@
   0: [mq]: 1.patch - test - 4.00
   ==== qref -m
   Date: 6 0
+  
   Drei
   
   diff -r ... 3
@@ -272,6 +275,7 @@
   0: [mq]: 1.patch - test - 4.00
   ==== qref -d
   Date: 7 0
+  
   Drei
   
   diff -r ... 3
@@ -283,6 +287,7 @@
   0: [mq]: 1.patch - test - 4.00
   ==== qref -d -m
   Date: 8 0
+  
   Three (again)
   
   diff -r ... 3
diff --git a/tests/test-mq-header-from.t b/tests/test-mq-header-from.t
--- a/tests/test-mq-header-from.t
+++ b/tests/test-mq-header-from.t
@@ -176,6 +176,7 @@
   0: [mq]: 1.patch - mary
   ==== qnew -U -m
   From: test
+  
   Three
   
   2: Three - test
@@ -184,6 +185,7 @@
   ==== qref
   adding 3
   From: test
+  
   Three
   
   diff -r ... 3
@@ -196,6 +198,7 @@
   0: [mq]: 1.patch - mary
   ==== qref -m
   From: test
+  
   Drei
   
   diff -r ... 3
@@ -208,6 +211,7 @@
   0: [mq]: 1.patch - mary
   ==== qref -u
   From: mary
+  
   Drei
   
   diff -r ... 3
@@ -220,6 +224,7 @@
   0: [mq]: 1.patch - mary
   ==== qref -u -m
   From: maria
+  
   Three (again)
   
   diff -r ... 3