diff --git a/ecdh.cc b/ecdh.cc
index 5d1f6e6..e8f0890 100644
--- a/ecdh.cc
+++ b/ecdh.cc
@@ -86,7 +86,8 @@ NAN_METHOD(Derive) {
   }
 
   uint8_t* shared = (uint8_t *)malloc(PRIVKEY_SIZE);
-  if (derive((uint8_t *)privkey_a, (uint8_t *)pubkey_b, shared)) {
+  if (shared == NULL ||
+      derive((uint8_t *)privkey_a, (uint8_t *)pubkey_b, shared)) {
     free(shared);
     return NanThrowError("Internal error");
   }
diff --git a/package.json b/package.json
index 23cc395..3988349 100644
--- a/package.json
+++ b/package.json
@@ -25,6 +25,7 @@
     "crypto",
     "cryptography",
     "secp256k1",
+    "K-256",
     "elliptic",
     "curve"
   ],