diff --git a/http/http.go b/http/http.go
index 14ddc1c..5cd241a 100644
--- a/http/http.go
+++ b/http/http.go
@@ -17,6 +17,7 @@ import (
 )
 
 var (
+	ErrNoTLSConnection  = errors.New("no tls connection")
 	ErrEmptyHostAddress = errors.New("empty host addr")
 )
 
@@ -75,6 +76,9 @@ var DefaultClient = http.Client{
 				_ = tlsConn.Close()
 				tlsConn = nil
 			}
+			if tlsConn == nil {
+				return nil, ErrNoTLSConnection
+			}
 			return tlsConn, err
 		},
 	},
diff --git a/http2/http2.go b/http2/http2.go
index a4122fb..fae446b 100644
--- a/http2/http2.go
+++ b/http2/http2.go
@@ -18,6 +18,7 @@ import (
 )
 
 var (
+	ErrNoTLSConnection  = errors.New("no tls connection")
 	ErrEmptyHostAddress = errors.New("empty host addr")
 )
 
@@ -74,6 +75,9 @@ var DefaultClient = http.Client{
 				_ = tlsConn.Close()
 				tlsConn = nil
 			}
+			if tlsConn == nil {
+				return nil, ErrNoTLSConnection
+			}
 			return tlsConn, err
 		},
 	},