diff --git a/library/x509_crt.c b/library/x509_crt.c
index 162281dfa..4418dab76 100644
--- a/library/x509_crt.c
+++ b/library/x509_crt.c
@@ -1585,8 +1585,7 @@ int mbedtls_x509_crt_parse_path(mbedtls_x509_crt *chain, const char *path)
             continue;
         }
         w_ret = WideCharToMultiByte(CP_ACP, 0, file_data.cFileName,
-                                    -1, p, (int) len - 1,
-                                    NULL, NULL);
+                                    -1, p, (int) len, NULL, NULL);
         if (w_ret == 0) {
             ret = MBEDTLS_ERR_X509_FILE_IO_ERROR;
             goto cleanup;