diff --git a/src/impl/tlstransport.cpp b/src/impl/tlstransport.cpp
index b3aec3da3..68ea06e26 100644
--- a/src/impl/tlstransport.cpp
+++ b/src/impl/tlstransport.cpp
@@ -338,7 +338,7 @@ TlsTransport::TlsTransport(variant<shared_ptr<TcpTransport>, shared_ptr<HttpProx
 			} else {
 				// *cacert is a PEM content
 				mbedtls::check(mbedtls_x509_crt_parse(
-				    &mCacert, (const unsigned char *)cacert->data(), cacert->size()));
+				    &mCacert, (reinterpret_cast<const unsigned char *>(cacert->data()), cacert->size()));
 			}
 			mbedtls_ssl_conf_ca_chain(&mConf, &mCacert, NULL);
 		}