diff --git a/DMCompiler/DM/DMExpression.cs b/DMCompiler/DM/DMExpression.cs
index 73de3895ba..41c7448bfc 100644
--- a/DMCompiler/DM/DMExpression.cs
+++ b/DMCompiler/DM/DMExpression.cs
@@ -138,10 +138,10 @@ private void VerifyArgType(DMCompiler compiler, DMProc targetProc, int index, st
     }
 }
 
-internal readonly struct ExpressionContext(DMCompiler compiler, DMObject type, DMProc proc) {
+internal readonly struct ExpressionContext(DMCompiler compiler, DMObject type, DMProc? proc) {
     public readonly DMCompiler Compiler = compiler;
     public readonly DMObject Type = type;
-    public readonly DMProc Proc = proc;
+    public readonly DMProc? Proc = proc;
 
     public DMObjectTree ObjectTree => Compiler.DMObjectTree;
 }