diff --git a/lib/ykpiv.c b/lib/ykpiv.c
index adcbb0c..477582a 100644
--- a/lib/ykpiv.c
+++ b/lib/ykpiv.c
@@ -390,9 +390,9 @@ ykpiv_rc ykpiv_authenticate(ykpiv_state *state, unsigned const char *key) {
   /* get a challenge from the card */
   {
     memset(apdu.raw, 0, sizeof(apdu));
-    apdu.st.ins = 0x87;
-    apdu.st.p1 = 0x03; /* triple des */
-    apdu.st.p2 = 0x9b; /* management key */
+    apdu.st.ins = YKPIV_INS_AUTHENTICATE;
+    apdu.st.p1 = YKPIV_ALGO_3DES; /* triple des */
+    apdu.st.p2 = YKPIV_KEY_CARDMGM; /* management key */
     apdu.st.lc = 0x04;
     apdu.st.data[0] = 0x7c;
     apdu.st.data[1] = 0x02;