diff --git a/src/script_opt/ZAM/Compile.h b/src/script_opt/ZAM/Compile.h
index e6bce25b9e..edfeff65bf 100644
--- a/src/script_opt/ZAM/Compile.h
+++ b/src/script_opt/ZAM/Compile.h
@@ -220,10 +220,15 @@ private:
 	const ZAMStmt CompileInExpr(const NameExpr* n1, const ListExpr* l, const NameExpr* n2,
 	                            const ConstExpr* c);
 
-	const ZAMStmt CompileIndex(const NameExpr* n1, const NameExpr* n2, const ListExpr* l);
-	const ZAMStmt CompileIndex(const NameExpr* n1, const ConstExpr* c, const ListExpr* l);
+	const ZAMStmt CompileIndex(const NameExpr* n1, const NameExpr* n2, const ListExpr* l,
+	                           bool in_when);
+	const ZAMStmt CompileIndex(const NameExpr* n1, const ConstExpr* c, const ListExpr* l,
+	                           bool in_when);
 	const ZAMStmt CompileIndex(const NameExpr* n1, int n2_slot, const TypePtr& n2_type,
-	                           const ListExpr* l);
+	                           const ListExpr* l, bool in_when);
+
+	const ZAMStmt BuildLambda(const NameExpr* n, LambdaExpr* le);
+	const ZAMStmt BuildLambda(int n_slot, LambdaExpr* le);
 
 	// Second argument is which instruction slot holds the branch target.
 	const ZAMStmt GenCond(const Expr* e, int& branch_v);
diff --git a/src/script_opt/ZAM/Expr.cc b/src/script_opt/ZAM/Expr.cc
index ebcd3bda6b..6982292755 100644
--- a/src/script_opt/ZAM/Expr.cc
+++ b/src/script_opt/ZAM/Expr.cc
@@ -1053,10 +1053,13 @@ const ZAMStmt ZAMCompiler::DoCall(const CallExpr* c, const NameExpr* n)
 	if ( ! z.aux )
 		z.aux = new ZInstAux(0);
 
-	z.aux->can_change_globals = true;
+	z.aux->can_change_non_locals = true;
 
 	z.call_expr = c;
 
+	if ( in_when )
+		z.SetType(n->GetType());
+
 	if ( ! indirect || func_id->IsGlobal() )
 		{
 		z.aux->id_val = func_id;