diff --git a/errcheck/errcheck.go b/errcheck/errcheck.go
index b3a67d4..0a4067f 100644
--- a/errcheck/errcheck.go
+++ b/errcheck/errcheck.go
@@ -543,6 +543,7 @@ func readfile(filename string) []string {
 	if err != nil {
 		return nil
 	}
+	defer f.Close()
 
 	var lines []string
 	var scanner = bufio.NewScanner(f)