diff --git a/manifests/fragment.pp b/manifests/fragment.pp
index f9ee2a7ca..7b13b0042 100644
--- a/manifests/fragment.pp
+++ b/manifests/fragment.pp
@@ -57,7 +57,13 @@
   if $backup {
     warning('The $backup parameter to concat::fragment is deprecated and has no effect')
   }
+
   $my_backup = concat_getparam(Concat[$target], 'backup')
+  $_backup = $my_backup ? {
+    ''      => undef,
+    default => $my_backup
+  }
+
   if $ensure == undef {
     $my_ensure = concat_getparam(Concat[$target], 'ensure')
   } else {
@@ -119,7 +125,7 @@
     mode    => $fragmode,
     source  => $source,
     content => $content,
-    backup  => $my_backup,
+    backup  => $_backup,
     replace => true,
     alias   => "concat_fragment_${name}",
     notify  => Exec["concat_${target}"]