diff --git a/src/base/bitunion.hh b/src/base/bitunion.hh
index f640fa3b19..190c1a5e13 100644
--- a/src/base/bitunion.hh
+++ b/src/base/bitunion.hh
@@ -85,6 +85,9 @@ namespace BitfieldBackend
         template<int first, int last=first>
         class Bitfield : public BitfieldBase<Type>
         {
+            static_assert(first >= last,
+                          "Bitfield ranges must be specified as <msb, lsb>");
+
           public:
             operator const uint64_t () const
             {