diff --git a/artiq/compiler/testbench/llvmgen.py b/artiq/compiler/testbench/llvmgen.py
index 21f010a76..ed318b897 100644
--- a/artiq/compiler/testbench/llvmgen.py
+++ b/artiq/compiler/testbench/llvmgen.py
@@ -21,7 +21,8 @@ def main():
     # Add main so that the result can be executed with lli
     llmain = ll.Function(llmod, ll.FunctionType(ll.VoidType(), []), "main")
     llbuilder = ll.IRBuilder(llmain.append_basic_block("entry"))
-    llbuilder.call(llmod.get_global(llmod.name + ".__modinit__"), [])
+    llbuilder.call(llmod.get_global(llmod.name + ".__modinit__"), [
+                    ll.Constant(ll.IntType(8).as_pointer(), None)])
     llbuilder.ret_void()
 
     print(llmod)