diff --git a/Wox.Plugin.System/Calculator.cs b/Wox.Plugin.System/Calculator.cs
index a1863507a2..4a333ba8ca 100644
--- a/Wox.Plugin.System/Calculator.cs
+++ b/Wox.Plugin.System/Calculator.cs
@@ -34,7 +34,7 @@ namespace Wox.Plugin.System
         protected override List<Result> QueryInternal(Query query)
         {
             if (string.IsNullOrEmpty(query.RawQuery)
-                || query.RawQuery.Length < 2          // don't affect when user only input "e" or "i" keyword
+                || query.RawQuery.Length <= 2          // don't affect when user only input "e" or "i" keyword
                 || !regValidExpressChar.IsMatch(query.RawQuery) 
                 || !IsBracketComplete(query.RawQuery)) return new List<Result>();