diff --git a/m-serial-json.h b/m-serial-json.h
index 3484b0cf..b0636bee 100644
--- a/m-serial-json.h
+++ b/m-serial-json.h
@@ -972,6 +972,7 @@ m_ser1al_str_json_read_array_start(m_serial_local_t local, m_serial_read_t seria
   m_ser1al_str_json_skip(f);
   if (M_UNLIKELY (**f == ']')) {
     c = m_ser1al_str_json_getc(f);
+    assert( c == ']');
     return M_SERIAL_OK_DONE;
   } else {
     return M_SERIAL_OK_CONTINUE;
@@ -1013,6 +1014,7 @@ m_ser1al_str_json_read_map_start(m_serial_local_t local, m_serial_read_t serial,
   m_ser1al_str_json_skip(f);
   if (M_UNLIKELY (**f == '}')) {
     c = m_ser1al_str_json_getc(f);
+    assert(c == '}');
     return M_SERIAL_OK_DONE;
   } else {
     return M_SERIAL_OK_CONTINUE;
diff --git a/m-string.h b/m-string.h
index 6e0890f4..a2b5ddfb 100644
--- a/m-string.h
+++ b/m-string.h
@@ -888,7 +888,6 @@ m_str1ng_replace_all_cstr_1ge2 (m_string_t v, const char str1[], size_t str1len,
       memmove(dst, src, (size_t) (occ - src));
     }
     dst += (occ - src);
-    src  = occ;
     // Copy the replaced string
     memcpy(dst, str2, str2len);
     dst += str2len;