diff --git a/main.go b/main.go
index 4218595..4d0113f 100644
--- a/main.go
+++ b/main.go
@@ -125,7 +125,9 @@ type file interface {
 
 // replaced by testing functions.
 var openFile = func(name string) (file, error) {
-	return os.OpenFile(name, os.O_RDWR, 0666)
+	// The permission bits (third argument) are only used when O_CREATE is set.
+	// Since we only open existing files, 0 is passed to make that clear.
+	return os.OpenFile(name, os.O_RDWR, 0)
 }
 
 func processFile(path string, rewrite, doDiff bool) (foundDiff bool, err error) {
diff --git a/main_test.go b/main_test.go
index 76c4bb7..3bbba5a 100644
--- a/main_test.go
+++ b/main_test.go
@@ -5,7 +5,7 @@
 // http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to writing, software distributed
-// under the License is distributed on a "AS IS" BASIS, WITHOUT WARRANTIES OR
+// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
 // CONDITIONS OF ANY KIND, either express or implied.
 //
 // See the License for the specific language governing permissions and
@@ -120,7 +120,6 @@ func TestEmbedFiles(t *testing.T) {
 		if got := f.buf.String(); tt.out != got {
 			t.Errorf("case [%s]: expected output \n%q; got\n%q", tt.name, tt.out, got)
 		}
-
 	}
 }