diff --git a/lib/ykpiv.c b/lib/ykpiv.c
index 67d8f79..b1b0a1f 100644
--- a/lib/ykpiv.c
+++ b/lib/ykpiv.c
@@ -520,6 +520,8 @@ ykpiv_rc ykpiv_list_readers(ykpiv_state *state, char *readers, size_t *len) {
 
   if (num_readers > *len) {
     num_readers = (pcsc_word)*len;
+  } else if (num_readers < *len) {
+    *len = (size_t)num_readers;
   }
 
   rc = SCardListReaders(state->context, NULL, readers, &num_readers);
diff --git a/ykcs11/ykcs11.c b/ykcs11/ykcs11.c
index 6bbdb1a..9a817bf 100644
--- a/ykcs11/ykcs11.c
+++ b/ykcs11/ykcs11.c
@@ -86,6 +86,8 @@ CK_DEFINE_FUNCTION(CK_RV, C_Initialize)(
 
   DIN;
 
+  memset(readers, '\0', sizeof(readers));
+
   if (piv_state != NULL)
     return CKR_CRYPTOKI_ALREADY_INITIALIZED;