diff --git a/src/core/lib/promise/detail/basic_seq.h b/src/core/lib/promise/detail/basic_seq.h
index e03bb6d475b..016102d28f7 100644
--- a/src/core/lib/promise/detail/basic_seq.h
+++ b/src/core/lib/promise/detail/basic_seq.h
@@ -17,6 +17,8 @@
 
 #include <grpc/impl/codegen/port_platform.h>
 
+#include <cassert>
+
 #include "absl/types/variant.h"
 #include "absl/utility/utility.h"