diff --git a/src/libopensc/card-authentic.c b/src/libopensc/card-authentic.c
index 2322bc94..99332e55 100644
--- a/src/libopensc/card-authentic.c
+++ b/src/libopensc/card-authentic.c
@@ -819,7 +819,7 @@ authentic_read_binary(struct sc_card *card, unsigned int idx,
 	struct sc_context *ctx = card->ctx;
 	struct sc_apdu apdu;
 	size_t sz, rest, ret_count = 0;
-	int rv = SC_SUCCESS;
+	int rv = SC_ERROR_INVALID_ARGUMENTS;
 
 	LOG_FUNC_CALLED(ctx);
 	sc_log(ctx,
@@ -865,7 +865,7 @@ authentic_write_binary(struct sc_card *card, unsigned int idx,
 	struct sc_context *ctx = card->ctx;
 	struct sc_apdu apdu;
 	size_t sz, rest;
-	int rv = SC_SUCCESS;
+	int rv = SC_ERROR_INVALID_ARGUMENTS;
 
 	LOG_FUNC_CALLED(ctx);
 	sc_log(ctx,
@@ -908,7 +908,7 @@ authentic_update_binary(struct sc_card *card, unsigned int idx,
 	struct sc_context *ctx = card->ctx;
 	struct sc_apdu apdu;
 	size_t sz, rest;
-	int rv = SC_SUCCESS;
+	int rv = SC_ERROR_INVALID_ARGUMENTS;
 
 	LOG_FUNC_CALLED(ctx);
 	sc_log(ctx,
diff --git a/src/tools/opensc-explorer.c b/src/tools/opensc-explorer.c
index a4edb88f..0da867f5 100644
--- a/src/tools/opensc-explorer.c
+++ b/src/tools/opensc-explorer.c
@@ -490,6 +490,7 @@ static int do_ls(int argc, char **argv)
 	u8 buf[256], *cur = buf;
 	int r, count;
 
+	memset(buf, 0, sizeof buf);
 	r = sc_lock(card);
 	if (r == SC_SUCCESS)
 		r = sc_list_files(card, buf, sizeof(buf));