diff --git a/src/config_format/flb_cf_fluentbit.c b/src/config_format/flb_cf_fluentbit.c
index 3b262ba9fec..5822011b898 100644
--- a/src/config_format/flb_cf_fluentbit.c
+++ b/src/config_format/flb_cf_fluentbit.c
@@ -522,7 +522,7 @@ static int read_config(struct flb_cf *cf, struct local_ctx *ctx,
 #ifndef FLB_HAVE_STATIC_CONF
         else {
             /* resize the line buffer */
-            bufsize *= 2;
+            bufsize += FLB_DEFAULT_CF_BUF_SIZE;
             buf = flb_realloc(buf, bufsize);
             if (!buf) {
                 flb_error("failed to resize line buffer to %zu", bufsize);