diff --git a/.gitignore b/.gitignore
index 496ee2ca..af56f610 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,2 @@
-.DS_Store
\ No newline at end of file
+.DS_Store
+.idea/
diff --git a/src/Lua/LuaFunction.cs b/src/Lua/LuaFunction.cs
index 2c1fae5a..6ebaf5db 100644
--- a/src/Lua/LuaFunction.cs
+++ b/src/Lua/LuaFunction.cs
@@ -5,7 +5,7 @@ namespace Lua;
 
 public class LuaFunction(string name, Func<LuaFunctionExecutionContext, Memory<LuaValue>, CancellationToken, ValueTask<int>> func)
 {
-    public string Name { get; } = name;
+    public string Name { get; set; } = name;
     internal Func<LuaFunctionExecutionContext, Memory<LuaValue>, CancellationToken, ValueTask<int>> Func { get; } = func;
 
     public LuaFunction(Func<LuaFunctionExecutionContext, Memory<LuaValue>, CancellationToken, ValueTask<int>> func) : this("anonymous", func)
@@ -31,4 +31,4 @@ public async ValueTask<int> InvokeAsync(LuaFunctionExecutionContext context, Mem
             context.Thread.PopCallStackFrame();
         }
     }
-}
\ No newline at end of file
+}
diff --git a/src/Lua/Runtime/Tracebacks.cs b/src/Lua/Runtime/Tracebacks.cs
index 2a97ea19..20732b8b 100644
--- a/src/Lua/Runtime/Tracebacks.cs
+++ b/src/Lua/Runtime/Tracebacks.cs
@@ -24,7 +24,8 @@ internal SourcePosition LastPosition
                 if (lastFunc is Closure closure)
                 {
                     var p = closure.Proto;
-                    return p.SourcePositions[frame.CallerInstructionIndex];
+                    if (frame.CallerInstructionIndex < p.SourcePositions.Length)
+                        return p.SourcePositions[frame.CallerInstructionIndex];
                 }
             }
 
@@ -66,4 +67,4 @@ public override string ToString()
 
         return list.AsSpan().ToString();
     }
-}
\ No newline at end of file
+}
diff --git a/src/Lua/Standard/StringLibrary.cs b/src/Lua/Standard/StringLibrary.cs
index 9eeb1bb1..a33f03db 100644
--- a/src/Lua/Standard/StringLibrary.cs
+++ b/src/Lua/Standard/StringLibrary.cs
@@ -1,5 +1,6 @@
 using System.Text;
 using Lua.Internal;
+using System.Globalization;
 
 namespace Lua.Standard;
 
@@ -148,6 +149,9 @@ public ValueTask<int> Find(LuaFunctionExecutionContext context, Memory<LuaValue>
 
     public async ValueTask<int> Format(LuaFunctionExecutionContext context, Memory<LuaValue> buffer, CancellationToken cancellationToken)
     {
+        var currentCulture = CultureInfo.CurrentCulture;
+        CultureInfo.CurrentCulture = CultureInfo.InvariantCulture;
+
         var format = context.GetArgument<string>(0);
 
         // TODO: pooling StringBuilder
@@ -419,6 +423,9 @@ public async ValueTask<int> Format(LuaFunctionExecutionContext context, Memory<L
 
 
         buffer.Span[0] = builder.ToString();
+
+        CultureInfo.CurrentCulture = currentCulture;
+
         return 1;
     }
 
@@ -629,4 +636,4 @@ public ValueTask<int> Upper(LuaFunctionExecutionContext context, Memory<LuaValue
         buffer.Span[0] = s.ToUpper();
         return new(1);
     }
-}
\ No newline at end of file
+}
diff --git a/tests/Lua.Tests/tests-lua/strings.lua b/tests/Lua.Tests/tests-lua/strings.lua
index fd13d450..f38c3681 100644
--- a/tests/Lua.Tests/tests-lua/strings.lua
+++ b/tests/Lua.Tests/tests-lua/strings.lua
@@ -133,6 +133,7 @@ assert(string.format("%c",34)..string.format("%c",48)..string.format("%c",90)..s
        string.format("%c%c%c%c", 34, 48, 90, 100))
 assert(string.format("%s\0 is not \0%s", 'not be', 'be') == 'not be\0 is not \0be')
 assert(string.format("%%%d %010d", 10, 23) == "%10 0000000023")
+print("10.3 as string is: " .. string.format("%f", 10.3) .. " and as number: " .. tostring(tonumber(string.format("%f", 10.3))))
 assert(tonumber(string.format("%f", 10.3)) == 10.3)
 x = string.format('"%-50s"', 'a')
 assert(#x == 52)
@@ -280,5 +281,3 @@ assert(os.setlocale(nil, "numeric") == 'C')
 end
 
 print('OK')
-
-