diff --git a/format.cc b/format.cc
index 6bdceaa0..1ca17f9c 100644
--- a/format.cc
+++ b/format.cc
@@ -44,6 +44,7 @@
 using std::size_t;
 using fmt::Formatter;
 using fmt::FormatSpec;
+using fmt::StringRef;
 
 #if _MSC_VER
 # undef snprintf