diff --git a/format.cc b/format.cc
index 37f07a1a..ae38e0da 100644
--- a/format.cc
+++ b/format.cc
@@ -37,6 +37,8 @@
 #include <cmath>
 #include <cstdarg>
 
+using fmt::ULongLong;
+
 namespace {
 
 #ifndef _MSC_VER