diff --git a/manifests/unit_file.pp b/manifests/unit_file.pp
index 237e27a9..cf7aad6d 100644
--- a/manifests/unit_file.pp
+++ b/manifests/unit_file.pp
@@ -92,8 +92,12 @@
 
   if $enable == 'mask' {
     $_target = '/dev/null'
+    $_content = undef
+    $_source  = undef
   } else {
     $_target = $target
+    $_content = $content
+    $_source  = $source
   }
 
   if $_target {
@@ -104,8 +108,8 @@
 
   file { "${path}/${name}":
     ensure                  => $_ensure,
-    content                 => $content,
-    source                  => $source,
+    content                 => $_content,
+    source                  => $_source,
     target                  => $_target,
     owner                   => $owner,
     group                   => $group,
diff --git a/spec/defines/manage_unit_spec.rb b/spec/defines/manage_unit_spec.rb
index 003e0acc..8541df11 100644
--- a/spec/defines/manage_unit_spec.rb
+++ b/spec/defines/manage_unit_spec.rb
@@ -127,6 +127,25 @@
           }
         end
 
+        context 'when masking a unit' do
+          let(:title) { 'tmpfs.mount' }
+
+          let(:params) do
+            {
+              enable: 'mask',
+            }
+          end
+
+          it { is_expected.to compile.with_all_deps }
+
+          it {
+            is_expected.to contain_file('/etc/systemd/system/tmpfs.mount').with(
+              ensure: 'link',
+              target: '/dev/null'
+            )
+          }
+        end
+
         context 'on a swap' do
           let(:title) { 'file.swap' }