diff --git a/src/lib_json/json_tool.h b/src/lib_json/json_tool.h
index e6d4e92..2de0d83 100644
--- a/src/lib_json/json_tool.h
+++ b/src/lib_json/json_tool.h
@@ -43,7 +43,7 @@ static inline std::string codePointToUTF8(unsigned int cp) {
   return result;
 }
 
-/// Returns true if ch is a control character (in range [0,32[).
+/// Returns true if ch is a control character (in range [0,32]).
 static inline bool isControlCharacter(char ch) { return ch > 0 && ch <= 0x1F; }
 
 enum {