diff --git a/src/DelegateDecompiler/OptimizeExpressionVisitor.cs b/src/DelegateDecompiler/OptimizeExpressionVisitor.cs
index 106a388a..96331bc2 100644
--- a/src/DelegateDecompiler/OptimizeExpressionVisitor.cs
+++ b/src/DelegateDecompiler/OptimizeExpressionVisitor.cs
@@ -460,7 +460,7 @@ protected override Expression VisitMethodCall(MethodCallExpression node)
             {
                 if (node.Method.Name == nameof(Expression.Constant) && 
                     node.Method.DeclaringType == typeof(Expression) &&
-                    node.Arguments[0] is Expression parameter)
+                    node.Arguments[0] is ParameterExpression parameter)
                 {
                     return Expression.Constant(parameter);
                 }
diff --git a/test.cmd b/test.cmd
index 9596647f..2a985241 100644
--- a/test.cmd
+++ b/test.cmd
@@ -4,11 +4,11 @@ nunit3-console ^
  src\DelegateDecompiler.Tests\bin\Release\net45\DelegateDecompiler.Tests.dll ^
  src\DelegateDecompiler.Tests.VB\bin\Release\net45\DelegateDecompiler.Tests.VB.dll ^
  src\DelegateDecompiler.EntityFramework.Tests\bin\Release\net45\DelegateDecompiler.EntityFramework.Tests.dll ^
- --result=DelegateDecompiler.testsresults.xml;format=AppVeyor
+ --result=DelegateDecompiler.testsresults.xml;format=AppVeyor && ^
 
-dotnet test --no-build -c Release -f netcoreapp3.1 src\DelegateDecompiler.Tests 
-dotnet test --no-build -c Release -f netcoreapp3.1 src\DelegateDecompiler.Tests.VB
-dotnet test --no-build -c Release -f netcoreapp3.1 src\DelegateDecompiler.EntityFramework.Tests
-dotnet test --no-build -c Release -f netcoreapp3.1 src\DelegateDecompiler.EntityFrameworkCore.Tests
-dotnet test --no-build -c Release -f netcoreapp3.1 src\DelegateDecompiler.EntityFrameworkCore3.Tests
+dotnet test --no-build -c Release -f netcoreapp3.1 src\DelegateDecompiler.Tests && ^
+dotnet test --no-build -c Release -f netcoreapp3.1 src\DelegateDecompiler.Tests.VB && ^
+dotnet test --no-build -c Release -f netcoreapp3.1 src\DelegateDecompiler.EntityFramework.Tests && ^
+dotnet test --no-build -c Release -f netcoreapp3.1 src\DelegateDecompiler.EntityFrameworkCore.Tests && ^
+dotnet test --no-build -c Release -f netcoreapp3.1 src\DelegateDecompiler.EntityFrameworkCore3.Tests && ^
 dotnet test --no-build -c Release -f net5.0 src\DelegateDecompiler.EntityFrameworkCore5.Tests