diff --git a/src/event/ngx_event_openssl_stapling.c b/src/event/ngx_event_openssl_stapling.c
index 0bea5e7..7d0a170 100644
--- a/src/event/ngx_event_openssl_stapling.c
+++ b/src/event/ngx_event_openssl_stapling.c
@@ -227,7 +227,7 @@
         return NGX_ERROR;
     }
 
-    bio = BIO_new_file((char *) file->data, "r");
+    bio = BIO_new_file((char *) file->data, "rb");
     if (bio == NULL) {
         ngx_ssl_error(NGX_LOG_EMERG, ssl->log, 0,
                       "BIO_new_file(\"%s\") failed", file->data);