diff --git a/crypto/ecdh/ecdh.c b/crypto/ecdh/ecdh.c
index 14856db..4a1964a 100644
--- a/crypto/ecdh/ecdh.c
+++ b/crypto/ecdh/ecdh.c
@@ -75,33 +75,27 @@
 
 
 int ECDH_compute_key(void *out, size_t outlen, const EC_POINT *pub_key,
-                     EC_KEY *priv_key, void *(*KDF)(const void *in, size_t inlen,
-                                                void *out, size_t *outlen)) {
-  BN_CTX *ctx;
-  EC_POINT *tmp = NULL;
-  BIGNUM *x = NULL, *y = NULL;
-  const BIGNUM *priv;
-  const EC_GROUP *group;
-  int ret = -1;
-  size_t buflen;
-  uint8_t *buf = NULL;
-
-  if ((ctx = BN_CTX_new()) == NULL) {
-    goto err;
-  }
-  BN_CTX_start(ctx);
-  x = BN_CTX_get(ctx);
-  y = BN_CTX_get(ctx);
-
-  priv = EC_KEY_get0_private_key(priv_key);
+                     EC_KEY *priv_key,
+                     void *(*kdf)(const void *in, size_t inlen, void *out,
+                                  size_t *outlen)) {
+  const BIGNUM *const priv = EC_KEY_get0_private_key(priv_key);
   if (priv == NULL) {
     OPENSSL_PUT_ERROR(ECDH, ECDH_R_NO_PRIVATE_VALUE);
-    goto err;
+    return -1;
   }
 
-  group = EC_KEY_get0_group(priv_key);
+  BN_CTX *ctx = BN_CTX_new();
+  if (ctx == NULL) {
+    return -1;
+  }
+  BN_CTX_start(ctx);
 
-  tmp = EC_POINT_new(group);
+  int ret = -1;
+  size_t buflen = 0;
+  uint8_t *buf = NULL;
+
+  const EC_GROUP *const group = EC_KEY_get0_group(priv_key);
+  EC_POINT *tmp = EC_POINT_new(group);
   if (tmp == NULL) {
     OPENSSL_PUT_ERROR(ECDH, ERR_R_MALLOC_FAILURE);
     goto err;
@@ -112,7 +106,13 @@
     goto err;
   }
 
-  if (!EC_POINT_get_affine_coordinates_GFp(group, tmp, x, y, ctx)) {
+  BIGNUM *x = BN_CTX_get(ctx);
+  if (!x) {
+    OPENSSL_PUT_ERROR(ECDH, ERR_R_MALLOC_FAILURE);
+    goto err;
+  }
+
+  if (!EC_POINT_get_affine_coordinates_GFp(group, tmp, x, NULL, ctx)) {
     OPENSSL_PUT_ERROR(ECDH, ECDH_R_POINT_ARITHMETIC_FAILURE);
     goto err;
   }
@@ -129,33 +129,25 @@
     goto err;
   }
 
-  if (KDF != 0) {
-    if (KDF(buf, buflen, out, &outlen) == NULL) {
+  if (kdf != NULL) {
+    if (kdf(buf, buflen, out, &outlen) == NULL) {
       OPENSSL_PUT_ERROR(ECDH, ECDH_R_KDF_FAILED);
       goto err;
     }
-    ret = outlen;
   } else {
     /* no KDF, just copy as much as we can */
-    if (outlen > buflen) {
+    if (buflen < outlen) {
       outlen = buflen;
     }
     memcpy(out, buf, outlen);
-    ret = outlen;
   }
 
+  ret = outlen;
+
 err:
-  if (tmp) {
-    EC_POINT_free(tmp);
-  }
-  if (ctx) {
-    BN_CTX_end(ctx);
-  }
-  if (ctx) {
-    BN_CTX_free(ctx);
-  }
-  if (buf) {
-    OPENSSL_free(buf);
-  }
+  OPENSSL_free(buf);
+  EC_POINT_free(tmp);
+  BN_CTX_end(ctx);
+  BN_CTX_free(ctx);
   return ret;
 }
diff --git a/include/openssl/ecdh.h b/include/openssl/ecdh.h
index 878cbeb..5fe3ae9 100644
--- a/include/openssl/ecdh.h
+++ b/include/openssl/ecdh.h
@@ -80,14 +80,14 @@
 
 
 /* ECDH_compute_key calculates the shared key between |pub_key| and |priv_key|.
- * If |KDF| is not NULL, then it is called with the bytes of the shared key and
- * the parameter |out|. When |KDF| returns, the value of |*outlen| becomes the
+ * If |kdf| is not NULL, then it is called with the bytes of the shared key and
+ * the parameter |out|. When |kdf| returns, the value of |*outlen| becomes the
  * return value. Otherwise, as many bytes of the shared key as will fit are
  * copied directly to, at most, |outlen| bytes at |out|. It returns the number
  * of bytes written to |out|, or -1 on error. */
 OPENSSL_EXPORT int ECDH_compute_key(void *out, size_t outlen,
                                     const EC_POINT *pub_key, EC_KEY *priv_key,
-                                    void *(*KDF)(const void *in, size_t inlen,
+                                    void *(*kdf)(const void *in, size_t inlen,
                                                  void *out, size_t *outlen));