diff --git a/ir.c b/ir.c
index 13afbba..a641310 100644
--- a/ir.c
+++ b/ir.c
@@ -485,7 +485,7 @@ ir_function* ir_function_new(ir_builder* owner, int outtype)
     self->values = NULL;
     self->locals = NULL;
 
-    self->max_varargs = NULL;
+    self->max_varargs = 0;
 
     self->code_function_def = -1;
     self->allocated_locals = 0;