diff --git a/common/span.h b/common/span.h
index 85052af6473..3fbdfd1538a 100644
--- a/common/span.h
+++ b/common/span.h
@@ -42,7 +42,7 @@ namespace Common {
 	typedef typename super_type::reference reference; \
 	typedef typename super_type::const_reference const_reference;
 
-enum {
+enum : uint {
 	kSpanMaxSize = 0xFFFFFFFF,
 	kSpanKeepOffset = 0xFFFFFFFF
 };