diff --git a/src/serialize.h b/src/serialize.h
--- a/src/serialize.h
+++ b/src/serialize.h
@@ -606,7 +606,7 @@
 
 #define VARINT_MODE(obj, mode) Using<VarIntFormatter<mode>>(obj)
 #define VARINT(obj) Using<VarIntFormatter<VarIntMode::DEFAULT>>(obj)
-#define COMPACTSIZE(obj) CCompactSize(REF(obj))
+#define COMPACTSIZE(obj) Using<CompactSizeFormatter>(obj)
 #define LIMITED_STRING(obj, n) LimitedString<n>(REF(obj))
 
 /**
@@ -654,19 +654,25 @@
     }
 };
 
-class CCompactSize {
-protected:
-    uint64_t &n;
-
-public:
-    explicit CCompactSize(uint64_t &nIn) : n(nIn) {}
-
-    template <typename Stream> void Serialize(Stream &s) const {
-        WriteCompactSize<Stream>(s, n);
+/** Formatter for integers in CompactSize format. */
+struct CompactSizeFormatter {
+    template <typename Stream, typename I> void Unser(Stream &s, I &v) {
+        uint64_t n = ReadCompactSize<Stream>(s);
+        if (n < std::numeric_limits<I>::min() ||
+            n > std::numeric_limits<I>::max()) {
+            throw std::ios_base::failure("CompactSize exceeds limit of type");
+        }
+        v = n;
     }
 
-    template <typename Stream> void Unserialize(Stream &s) {
-        n = ReadCompactSize<Stream>(s);
+    template <typename Stream, typename I> void Ser(Stream &s, I v) {
+        static_assert(std::is_unsigned<I>::value,
+                      "CompactSize only supported for unsigned integers");
+        static_assert(std::numeric_limits<I>::max() <=
+                          std::numeric_limits<uint64_t>::max(),
+                      "CompactSize only supports 64-bit integers and below");
+
+        WriteCompactSize<Stream>(s, v);
     }
 };