diff --git a/crypto/fipsmodule/ec/ec_key.c b/crypto/fipsmodule/ec/ec_key.c
index d7acf969c..2d04d13cc 100644
--- a/crypto/fipsmodule/ec/ec_key.c
+++ b/crypto/fipsmodule/ec/ec_key.c
@@ -308,6 +308,9 @@ int EC_KEY_check_key(const EC_KEY *eckey) {
   }
 
   // Check the public and private keys match.
+  //
+  // NOTE: this is a FIPS pair-wise consistency check for the ECDH case. See SP
+  // 800-56Ar3, page 36.
   if (eckey->priv_key != NULL) {
     EC_RAW_POINT point;
     if (!ec_point_mul_scalar_base(eckey->group, &point,
diff --git a/include/openssl/ec_key.h b/include/openssl/ec_key.h
index 3a4085660..502bfc2d9 100644
--- a/include/openssl/ec_key.h
+++ b/include/openssl/ec_key.h
@@ -167,8 +167,9 @@ OPENSSL_EXPORT void EC_KEY_set_conv_form(EC_KEY *key,
 // about the problem can be found on the error stack.
 OPENSSL_EXPORT int EC_KEY_check_key(const EC_KEY *key);
 
-// EC_KEY_check_fips performs a signing pairwise consistency test (FIPS 140-2
-// 4.9.2). It returns one if it passes and zero otherwise.
+// EC_KEY_check_fips performs both a signing pairwise consistency test
+// (FIPS 140-2 4.9.2) and the consistency test from SP 800-56Ar3 section
+// 5.6.2.1.4. It returns one if it passes and zero otherwise.
 OPENSSL_EXPORT int EC_KEY_check_fips(const EC_KEY *key);
 
 // EC_KEY_set_public_key_affine_coordinates sets the public key in |key| to
@@ -194,7 +195,9 @@ OPENSSL_EXPORT size_t EC_KEY_key2buf(const EC_KEY *key,
 OPENSSL_EXPORT int EC_KEY_generate_key(EC_KEY *key);
 
 // EC_KEY_generate_key_fips behaves like |EC_KEY_generate_key| but performs
-// additional checks for FIPS compliance.
+// additional checks for FIPS compliance. This function is applicable when
+// generating keys for either signing/verification or key agreement because
+// both types of consistency check (PCT) are performed.
 OPENSSL_EXPORT int EC_KEY_generate_key_fips(EC_KEY *key);
 
 // EC_KEY_derive_from_secret deterministically derives a private key for |group|