1 files changed, 8 insertions, 2 deletions

diff --git a/py/vstr.c b/py/vstr.c
index 181b1c49b9..2e53744362 100644
--- a/py/vstr.c
+++ b/py/vstr.c
@@ -151,7 +151,7 @@ STATIC bool vstr_ensure_extra(vstr_t *vstr, size_t size) {
         if (vstr->fixed_buf) {
             return false;
         }
-        size_t new_alloc = ROUND_ALLOC((vstr->len + size) + 64);
+        size_t new_alloc = ROUND_ALLOC((vstr->len + size) + 16);
         char *new_buf = m_renew(char, vstr->buf, vstr->alloc, new_alloc);
         if (new_buf == NULL) {
             vstr->had_error = true;
@@ -181,9 +181,15 @@ char *vstr_add_len(vstr_t *vstr, size_t len) {
 
 // Doesn't increase len, just makes sure there is a null byte at the end
 char *vstr_null_terminated_str(vstr_t *vstr) {
-    if (vstr->had_error || !vstr_ensure_extra(vstr, 1)) {
+    if (vstr->had_error) {
         return NULL;
     }
+    // If there's no more room, add single byte
+    if (vstr->alloc == vstr->len) {
+        if (vstr_extend(vstr, 1) == NULL) {
+            return NULL;
+        }
+    }
     vstr->buf[vstr->len] = '\0';
     return vstr->buf;
 }