diff --git a/csharp/ql/test/library-tests/parameters/Parameters.cs b/csharp/ql/test/library-tests/parameters/Parameters.cs
index 2cbcd89f9e4..ebe17322bad 100644
--- a/csharp/ql/test/library-tests/parameters/Parameters.cs
+++ b/csharp/ql/test/library-tests/parameters/Parameters.cs
@@ -22,6 +22,9 @@ public class Parameters
     public void M14([Optional, DateTimeConstant(14L)] DateTime arg4) => throw null;
     public void M15([Optional, DateTimeConstant(10001L)] DateTime? arg5) => throw null;
     public void M16([Optional, DefaultParameterValue(6L)] long arg6) => throw null;
+    public void M17([Optional, DefaultParameterValue(null)] object arg7) => throw null;
+    public void M18([Optional, DefaultParameterValue(3)] int? arg8) => throw null;
+    public void M19([Optional, DecimalConstant(1, 0, 0, 0, 103)] decimal arg9) => throw null;
 
     public struct MyStruct { }
     public enum MyEnum { A = 1, B = 2 }
diff --git a/csharp/ql/test/library-tests/parameters/Parameters.cs_ b/csharp/ql/test/library-tests/parameters/Parameters.cs_
index 262cd57a755..8fce6f198c3 100644
--- a/csharp/ql/test/library-tests/parameters/Parameters.cs_
+++ b/csharp/ql/test/library-tests/parameters/Parameters.cs_
@@ -22,6 +22,9 @@ public class ParametersDll
     public void M14([Optional, DateTimeConstant(14L)] DateTime arg4) => throw null;
     public void M15([Optional, DateTimeConstant(10001L)] DateTime? arg5) => throw null;
     public void M16([Optional, DefaultParameterValue(6L)] long arg6) => throw null;
+    public void M17([Optional, DefaultParameterValue(null)] object arg7) => throw null;
+    public void M18([Optional, DefaultParameterValue(3)] int? arg8) => throw null;
+    public void M19([Optional, DecimalConstant(1, 0, 0, 0, 103)] decimal arg9) => throw null;
 
     public struct MyStruct { }
     public enum MyEnum { A = 1, B = 2 }
diff --git a/csharp/ql/test/library-tests/parameters/Parameters.dll b/csharp/ql/test/library-tests/parameters/Parameters.dll
index 41cf1188ca8..b40c91369cb 100644
Binary files a/csharp/ql/test/library-tests/parameters/Parameters.dll and b/csharp/ql/test/library-tests/parameters/Parameters.dll differ
diff --git a/csharp/ql/test/library-tests/parameters/Parameters.expected b/csharp/ql/test/library-tests/parameters/Parameters.expected
index 9ef92a0dac0..4ac08438d3a 100644
--- a/csharp/ql/test/library-tests/parameters/Parameters.expected
+++ b/csharp/ql/test/library-tests/parameters/Parameters.expected
@@ -36,6 +36,9 @@ withDefaultValue
 | Parameters.cs:22:17:22:19 | M14 | Parameters.cs:22:64:22:67 | arg4 | 0 | Parameters.cs:22:21:22:67 | object creation of type DateTime | - |
 | Parameters.cs:23:17:23:19 | M15 | Parameters.cs:23:68:23:71 | arg5 | 0 | Parameters.cs:23:21:23:71 | object creation of type DateTime | - |
 | Parameters.cs:24:17:24:19 | M16 | Parameters.cs:24:64:24:67 | arg6 | 0 | Parameters.cs:24:21:24:67 | 6 | 6 |
+| Parameters.cs:25:17:25:19 | M17 | Parameters.cs:25:68:25:71 | arg7 | 0 | Parameters.cs:25:21:25:71 | default | null |
+| Parameters.cs:26:17:26:19 | M18 | Parameters.cs:26:63:26:66 | arg8 | 0 | Parameters.cs:26:21:26:66 | 3 | 3 |
+| Parameters.cs:27:17:27:19 | M19 | Parameters.cs:27:74:27:77 | arg9 | 0 | Parameters.cs:27:21:27:77 | 10.3 | 10.3 |
 | Parameters.dll:0:0:0:0 | M2 | Parameters.dll:0:0:0:0 | b | 1 | Parameters.dll:0:0:0:0 | default | null |
 | Parameters.dll:0:0:0:0 | M2 | Parameters.dll:0:0:0:0 | c | 2 | Parameters.dll:0:0:0:0 | "default string" | default string |
 | Parameters.dll:0:0:0:0 | M3 | Parameters.dll:0:0:0:0 | a | 0 | Parameters.dll:0:0:0:0 | 1 | 1 |
@@ -60,6 +63,9 @@ withDefaultValue
 | Parameters.dll:0:0:0:0 | M14 | Parameters.dll:0:0:0:0 | arg4 | 0 | Parameters.dll:0:0:0:0 | object creation of type DateTime | - |
 | Parameters.dll:0:0:0:0 | M15 | Parameters.dll:0:0:0:0 | arg5 | 0 | Parameters.dll:0:0:0:0 | object creation of type DateTime | - |
 | Parameters.dll:0:0:0:0 | M16 | Parameters.dll:0:0:0:0 | arg6 | 0 | Parameters.dll:0:0:0:0 | 6 | 6 |
+| Parameters.dll:0:0:0:0 | M17 | Parameters.dll:0:0:0:0 | arg7 | 0 | Parameters.dll:0:0:0:0 | default | null |
+| Parameters.dll:0:0:0:0 | M18 | Parameters.dll:0:0:0:0 | arg8 | 0 | Parameters.dll:0:0:0:0 | 3 | 3 |
+| Parameters.dll:0:0:0:0 | M19 | Parameters.dll:0:0:0:0 | arg9 | 0 | Parameters.dll:0:0:0:0 | 10.3 | 10.3 |
 dateTimeDefaults
 | Parameters.cs:22:17:22:19 | M14 | Parameters.cs:22:64:22:67 | arg4 | Parameters.cs:22:21:22:67 | object creation of type DateTime | DateTime(long) | 14 |
 | Parameters.cs:23:17:23:19 | M15 | Parameters.cs:23:68:23:71 | arg5 | Parameters.cs:23:21:23:71 | object creation of type DateTime | DateTime(long) | 10001 |