diff --git a/crypto/ec/ec.c b/crypto/ec/ec.c
index 21a39405..ad47bb55 100644
--- a/crypto/ec/ec.c
+++ b/crypto/ec/ec.c
@@ -500,10 +500,9 @@ err:
 }
 
 int EC_GROUP_cmp(const EC_GROUP *a, const EC_GROUP *b, BN_CTX *ignored) {
-  if (a->curve_name == NID_undef || b->curve_name == NID_undef) {
-    return 0;
-  }
-  return a->curve_name == b->curve_name;
+  return a->curve_name == NID_undef ||
+         b->curve_name == NID_undef ||
+         a->curve_name != b->curve_name;
 }
 
 const EC_POINT *EC_GROUP_get0_generator(const EC_GROUP *group) {
diff --git a/crypto/evp/p_ec_asn1.c b/crypto/evp/p_ec_asn1.c
index 8967b502..670ee744 100644
--- a/crypto/evp/p_ec_asn1.c
+++ b/crypto/evp/p_ec_asn1.c
@@ -382,7 +382,11 @@ static int ec_copy_parameters(EVP_PKEY *to, const EVP_PKEY *from) {
 static int ec_cmp_parameters(const EVP_PKEY *a, const EVP_PKEY *b) {
   const EC_GROUP *group_a = EC_KEY_get0_group(a->pkey.ec),
                  *group_b = EC_KEY_get0_group(b->pkey.ec);
-  return EC_GROUP_cmp(group_a, group_b, NULL);
+  if (EC_GROUP_cmp(group_a, group_b, NULL) != 0) {
+    /* mismatch */
+    return 0;
+  }
+  return 1;
 }
 
 static void int_ec_free(EVP_PKEY *pkey) { EC_KEY_free(pkey->pkey.ec); }
diff --git a/include/openssl/ec.h b/include/openssl/ec.h
index c952d9a9..318ce0f0 100644
--- a/include/openssl/ec.h
+++ b/include/openssl/ec.h
@@ -115,7 +115,7 @@ OPENSSL_EXPORT int EC_GROUP_copy(EC_GROUP *dest, const EC_GROUP *src);
  * error. */
 OPENSSL_EXPORT EC_GROUP *EC_GROUP_dup(const EC_GROUP *a);
 
-/* EC_GROUP_cmp returns one if |a| and |b| are the same group and zero
+/* EC_GROUP_cmp returns zero if |a| and |b| are the same group and non-zero
  * otherwise. */
 OPENSSL_EXPORT int EC_GROUP_cmp(const EC_GROUP *a, const EC_GROUP *b,
                                 BN_CTX *ignored);