diff --git a/Upsilon/Binder/Binder.cs b/Upsilon/Binder/Binder.cs
index c19a147..de4b621 100644
--- a/Upsilon/Binder/Binder.cs
+++ b/Upsilon/Binder/Binder.cs
@@ -200,6 +200,12 @@ namespace Upsilon.Binder
             {
                 var variableExpression =(BoundVariableExpression) expression;
                 var function = (FunctionVariableSymbol)variableExpression.Variable.VariableSymbol;
+                if (function.Parameters.Length != parameters.Count)
+                {
+                    _diagnostics.LogError($"Invalid number of parameters for function '{function.Name}'. " +
+                                          $"Expected '{function.Parameters.Length}', got '{parameters.Count}'", e.Span);
+                    return new BoundLiteralExpression(new ScriptNull(), e.Span);
+                }
                 if (!function.IsBound)
                 {
                     Scope = new BoundScope(Scope);
diff --git a/Upsilon/Parser/ExpressionSyntax/FunctionCallExpressionSyntax.cs b/Upsilon/Parser/ExpressionSyntax/FunctionCallExpressionSyntax.cs
index 81fc2a1..76a7d3c 100644
--- a/Upsilon/Parser/ExpressionSyntax/FunctionCallExpressionSyntax.cs
+++ b/Upsilon/Parser/ExpressionSyntax/FunctionCallExpressionSyntax.cs
@@ -18,7 +18,7 @@ namespace Upsilon.Parser
             OpenParenthesis = openParenthesis;
             Parameters = parameters;
             CloseParenthesis = closeParenthesis;
-            Span = new TextSpan(Identifier.Span.Start, CloseParenthesis.Span.End - Identifier.Span.End);
+            Span = new TextSpan(Identifier.Span.Start, CloseParenthesis.Span.End - Identifier.Span.Start);
         }
 
         public override SyntaxKind Kind => SyntaxKind.FunctionCallExpression;
diff --git a/Upsilon/Parser/Parser.cs b/Upsilon/Parser/Parser.cs
index 57c69de..4a4bfe7 100644
--- a/Upsilon/Parser/Parser.cs
+++ b/Upsilon/Parser/Parser.cs
@@ -202,15 +202,15 @@ namespace Upsilon.Parser
             var functionToken = MatchToken(SyntaxKind.FunctionKeyword);
             var openParenthesis = MatchToken(SyntaxKind.OpenParenthesis);
             var variableBuilder = ImmutableArray.CreateBuilder<IdentifierToken>();
-            IdentifierToken lastIdentifier = null;
+            SyntaxToken current = null;
             while (Current.Kind != SyntaxKind.CloseParenthesis)
             {
-                var variableIdentifier = (IdentifierToken)MatchToken(SyntaxKind.Identifier);
-                if (lastIdentifier == variableIdentifier)
+                if (Current == current)
                 {
                     break;
                 }
-                lastIdentifier = variableIdentifier;
+                current = Current;
+                var variableIdentifier = (IdentifierToken)MatchToken(SyntaxKind.Identifier);
                 variableBuilder.Add(variableIdentifier);
                 if (Current.Kind == SyntaxKind.Comma)
                     NextToken();