diff --git a/tools/spec.py b/tools/spec.py
index f4e0b4a..d592287 100644
--- a/tools/spec.py
+++ b/tools/spec.py
@@ -852,6 +852,7 @@ def write_dispatch(dst: TextIO, q: List[Type], reg: Registry):
     #include <cruft/util/debug.hpp>
     
     #include <cstring>
+    #include <iostream>
 
     #pragma GCC diagnostic ignored "-Wunused-parameter"