diff --git a/src/build.py b/src/build.py
index 9227c1089..ac35d44f0 100644
--- a/src/build.py
+++ b/src/build.py
@@ -274,6 +274,7 @@ source = Split(
     renderer_common/render_thunk_extractor.cpp
     renderer_common/pattern_alignment.cpp
     util/math.cpp
+    util/mapped_memory_file.cpp
     value.cpp
     """
     )