diff --git a/lib/curl_gssapi.c b/lib/curl_gssapi.c
index ccc24e09b1..354fa00dea 100644
--- a/lib/curl_gssapi.c
+++ b/lib/curl_gssapi.c
@@ -435,7 +435,8 @@ static OM_uint32 stub_gss_indicate_mechs(
   return GSS_S_COMPLETE;
 }
 
-#ifdef HAVE_GSS_SET_NEG_MECHS
+#ifdef HAVE_GSS_SET_NEG_MECHS  /* MIT Kerberos 1.8+ (2010-03-02),
+                                  missing from Apple GSS, GNU GSS */
 static OM_uint32 stub_gss_set_neg_mechs(
   OM_uint32 *min,
   gss_cred_id_t cred_handle,
@@ -509,7 +510,8 @@ OM_uint32 Curl_gss_init_sec_context(struct Curl_easy *data,
     req_flags |= GSS_C_MUTUAL_FLAG;
 
   if(data->set.gssapi_delegation & CURLGSSAPI_DELEGATION_POLICY_FLAG) {
-#ifdef GSS_C_DELEG_POLICY_FLAG  /* MIT Kerberos 1.8+, missing from GNU GSS */
+#ifdef GSS_C_DELEG_POLICY_FLAG  /* MIT Kerberos 1.7+ (2009-06-02), Apple GSS,
+                                   missing from GNU GSS */
     req_flags |= GSS_C_DELEG_POLICY_FLAG;
 #else
     infof(data, "WARNING: support for CURLGSSAPI_DELEGATION_POLICY_FLAG not "