diff --git a/doc/src/sgml/libpq.sgml b/doc/src/sgml/libpq.sgml
index 8908f775df..41864c6cf1 100644
--- a/doc/src/sgml/libpq.sgml
+++ b/doc/src/sgml/libpq.sgml
@@ -2592,12 +2592,22 @@ const char *PQsslAttribute(const PGconn *conn, const char *attribute_name);
      <term><function>PQsslAttributeNames</function><indexterm><primary>PQsslAttributeNames</primary></indexterm></term>
      <listitem>
       <para>
-       Returns an array of SSL attribute names available.
+       Returns an array of SSL attribute names that can be used
+       in <function>PQsslAttribute()</function>.
        The array is terminated by a NULL pointer.
 <synopsis>
 const char * const * PQsslAttributeNames(const PGconn *conn);
 </synopsis>
       </para>
+
+      <para>
+       If <literal>conn</literal> is NULL, the attributes available for the
+       default SSL library are returned, or an empty list
+       if <application>libpq</application> was compiled without any SSL
+       support.  If <literal>conn</literal> is not NULL, the attributes
+       available for the SSL library in use for the connection are returned,
+       or an empty list if the connection is not encrypted.
+      </para>
      </listitem>
     </varlistentry>
 
diff --git a/src/interfaces/libpq/fe-secure-openssl.c b/src/interfaces/libpq/fe-secure-openssl.c
index 74b5c5987a..b42a908733 100644
--- a/src/interfaces/libpq/fe-secure-openssl.c
+++ b/src/interfaces/libpq/fe-secure-openssl.c
@@ -1730,7 +1730,7 @@ PQsslStruct(PGconn *conn, const char *struct_name)
 const char *const *
 PQsslAttributeNames(PGconn *conn)
 {
-	static const char *const result[] = {
+	static const char *const openssl_attrs[] = {
 		"library",
 		"key_bits",
 		"cipher",
@@ -1738,8 +1738,19 @@ PQsslAttributeNames(PGconn *conn)
 		"protocol",
 		NULL
 	};
+	static const char *const empty_attrs[] = {NULL};
 
-	return result;
+	if (!conn)
+	{
+		/* Return attributes of default SSL library */
+		return openssl_attrs;
+	}
+
+	/* No attrs for unencrypted connection */
+	if (conn->ssl == NULL)
+		return empty_attrs;
+
+	return openssl_attrs;
 }
 
 const char *