diff --git a/common/DetectorModules.h b/common/DetectorModules.h
index 9b3e23d78..fcadb5d09 100644
--- a/common/DetectorModules.h
+++ b/common/DetectorModules.h
@@ -3,6 +3,7 @@
 
 #pragma once
 
+#include <cstddef>
 #include <cstdint>
 #include <utility>
 #include <vector>