diff --git a/flang/include/flang/Common/enum-class.h b/flang/include/flang/Common/enum-class.h
index 41575d45091a8..8c254c8bc6a70 100644
--- a/flang/include/flang/Common/enum-class.h
+++ b/flang/include/flang/Common/enum-class.h
@@ -17,6 +17,7 @@
 #ifndef FORTRAN_COMMON_ENUM_CLASS_H_
 #define FORTRAN_COMMON_ENUM_CLASS_H_
 
+#include "flang/Common/variant.h"
 #include <array>
 #include <string>