diff --git a/lib/ykpiv.c b/lib/ykpiv.c
index a57d0e2..fac90dd 100644
--- a/lib/ykpiv.c
+++ b/lib/ykpiv.c
@@ -38,6 +38,9 @@
 #include "internal.h"
 #include "ykpiv.h"
 
+static ykpiv_rc ykpiv_send_data(ykpiv_state *state, unsigned char *apdu,
+    unsigned char *data, unsigned long *recv_len, int *sw);
+
 static void dump_hex(const unsigned char *buf, unsigned int len) {
   unsigned int i;
   for (i = 0; i < len; i++) {
@@ -275,7 +278,7 @@ ykpiv_rc ykpiv_transfer_data(ykpiv_state *state, const unsigned char *templ,
   return YKPIV_OK;
 }
 
-ykpiv_rc ykpiv_send_data(ykpiv_state *state, unsigned char *apdu,
+static ykpiv_rc ykpiv_send_data(ykpiv_state *state, unsigned char *apdu,
     unsigned char *data, unsigned long *recv_len, int *sw) {
   long rc;
   unsigned int send_len = (unsigned int)(apdu[4] + 5); /* magic numbers.. */
diff --git a/lib/ykpiv.h b/lib/ykpiv.h
index 6022a1a..a019ff9 100644
--- a/lib/ykpiv.h
+++ b/lib/ykpiv.h
@@ -68,8 +68,6 @@ extern "C"
 	ykpiv_rc ykpiv_transfer_data(ykpiv_state *state, const unsigned char *templ,
 			const unsigned char *in_data, long in_len,
 			unsigned char *out_data, unsigned long *out_len, int *sw);
-	ykpiv_rc ykpiv_send_data(ykpiv_state *state, unsigned char *apdu,
-			unsigned char *data, unsigned long *recv_len, int *sw);
 	ykpiv_rc ykpiv_authenticate(ykpiv_state *state, const unsigned char *key);
 	ykpiv_rc ykpiv_set_mgmkey(ykpiv_state *state, const unsigned char *new_key);
 	ykpiv_rc ykpiv_parse_key(ykpiv_state *state,
diff --git a/lib/ykpiv.map b/lib/ykpiv.map
index 532439e..619ea09 100644
--- a/lib/ykpiv.map
+++ b/lib/ykpiv.map
@@ -34,7 +34,6 @@ global:
 	ykpiv_done;
 	ykpiv_connect;
 	ykpiv_disconnect;
-	ykpiv_send_data;
 	ykpiv_transfer_data;
 	ykpiv_authenticate;
 	ykpiv_set_mgmkey;