diff --git a/src/codegen/compiler/event.cpp b/src/codegen/compiler/event.cpp
index fa714d115b..9e94787d03 100644
--- a/src/codegen/compiler/event.cpp
+++ b/src/codegen/compiler/event.cpp
@@ -319,6 +319,10 @@ class CallEvent: public Event {
       unsigned argumentIndex = 0;
 
       while (true) {
+        assert(c, arguments[index] == s->value);
+        assert(c,
+               argumentIndex + 1 >= arguments.count || arguments[index + 1]
+                                                       == s->next->value);
         unsigned footprint
             = (argumentIndex + 1 < arguments.count and s->value->nextWord
                == s->next->value)