--- a/src/java.base/share/classes/sun/security/ssl/DHKeyExchange.java	Tue Jun 19 15:53:35 2018 -0700
+++ b/src/java.base/share/classes/sun/security/ssl/DHKeyExchange.java	Wed Jun 20 09:41:50 2018 -0700
@@ -477,6 +477,12 @@
                     SSLMasterKeyDerivation mskd =
                             SSLMasterKeyDerivation.valueOf(
                                     context.negotiatedProtocol);
+                    if (mskd == null) {
+                        // unlikely
+                        throw new SSLHandshakeException(
+                            "No expected master key derivation for protocol: " +
+                            context.negotiatedProtocol.name);
+                    }
                     SSLKeyDerivation kd = mskd.createKeyDerivation(
                             context, preMasterSecret);
                     return kd.deriveKey("MasterSecret", params);