diff --git a/src/pkg/crypto/tls/tls.go b/src/pkg/crypto/tls/tls.go
index 6c67506..40156a0 100644
--- a/src/pkg/crypto/tls/tls.go
+++ b/src/pkg/crypto/tls/tls.go
@@ -27,9 +27,8 @@
 
 // Client returns a new TLS client side connection
 // using conn as the underlying transport.
-// Client interprets a nil configuration as equivalent to
-// the zero configuration; see the documentation of Config
-// for the defaults.
+// The config cannot be nil: users must set either ServerHostname or
+// InsecureSkipVerify in the config.
 func Client(conn net.Conn, config *Config) *Conn {
 	return &Conn{conn: conn, config: config, isClient: true}
 }