diff --git a/cmd/passlint/testdata/src/taint/taint.go b/cmd/passlint/testdata/src/taint/taint.go
index 76c5a3d..0535934 100644
--- a/cmd/passlint/testdata/src/taint/taint.go
+++ b/cmd/passlint/testdata/src/taint/taint.go
@@ -43,5 +43,5 @@ func (u Untrusted) Tags() map[string]string {
 }
 
 func (u Untrusted) Format(f fmt.State, verb rune) {
-	io.WriteString(f, "<untrusted:source>")
+	_, _ = io.WriteString(f, "<untrusted:source>")
 }