diff --git a/src/common/small_string.h b/src/common/small_string.h
index 744a71fbb..9fc6ace4c 100644
--- a/src/common/small_string.h
+++ b/src/common/small_string.h
@@ -353,12 +353,12 @@ public:
   static SmallStackString from_vformat(fmt::string_view fmt, fmt::format_args args);
 
 private:
-  char m_stack_buffer[L + 1];
+  char m_stack_buffer[L];
 
   ALWAYS_INLINE void init()
   {
     m_buffer = m_stack_buffer;
-    m_buffer_size = L + 1;
+    m_buffer_size = L;
 
 #ifdef _DEBUG
     std::memset(m_stack_buffer, 0, sizeof(m_stack_buffer));