diff --git a/src/cashaddrenc.cpp b/src/cashaddrenc.cpp
--- a/src/cashaddrenc.cpp
+++ b/src/cashaddrenc.cpp
@@ -17,26 +17,35 @@
 
 // Size of data-part in a pubkey/script cash address.
 // Consists of: 8 bits version + 160 bits hash.
-const size_t CASHADDR_GROUPED_SIZE = 34; /* 5 bit representation */
-const size_t CASHADDR_BYTES = 21;        /* 8 bit representation */
+const size_t CASHADDR_BYTES = 21; /* 8 bit representation */
 
 namespace {
 
 // Convert the data part to a 5 bit representation.
 template <class T>
-std::vector<uint8_t> PackAddrData(const T &id, uint8_t type,
-                                  size_t expectedSize) {
-    std::vector<uint8_t> data = {uint8_t(type << 3)};
+std::vector<uint8_t> PackAddrData(const T &id, uint8_t type) {
+    uint8_t version_byte = uint8_t(type << 3);
+    auto size = id.size();
+    auto offset = size > 40 ? 2 : 1;
+    uint8_t encoded_size = (size - 20 * offset) / (4 * offset);
+    if (offset == 2) {
+        encoded_size |= 0x04;
+    }
+    if ((size - 20 * offset) % (4 * offset) != 0) {
+        throw std::runtime_error("Error packing cashaddr: invalid hash length");
+    }
+    if (encoded_size < 0 && encoded_size > 7) {
+        throw std::runtime_error("Error packing cashaddr: invalid hash length");
+    }
+
+    version_byte |= encoded_size;
+    std::vector<uint8_t> data = {version_byte};
     data.insert(data.end(), id.begin(), id.end());
 
     std::vector<uint8_t> converted;
-    converted.reserve(expectedSize);
+    converted.reserve((size + 1) * 8 / 5);
     ConvertBits<8, 5, true>(converted, begin(data), end(data));
 
-    if (converted.size() != expectedSize) {
-        throw std::runtime_error("Error packing cashaddr");
-    }
-
     return converted;
 }
 
@@ -46,14 +55,12 @@
     CashAddrEncoder(const CChainParams &p) : params(p) {}
 
     std::string operator()(const CKeyID &id) const {
-        std::vector<uint8_t> data =
-            PackAddrData(id, PUBKEY_TYPE, CASHADDR_GROUPED_SIZE);
+        std::vector<uint8_t> data = PackAddrData(id, PUBKEY_TYPE);
         return cashaddr::Encode(params.CashAddrPrefix(), data);
     }
 
     std::string operator()(const CScriptID &id) const {
-        std::vector<uint8_t> data =
-            PackAddrData(id, SCRIPT_TYPE, CASHADDR_GROUPED_SIZE);
+        std::vector<uint8_t> data = PackAddrData(id, SCRIPT_TYPE);
         return cashaddr::Encode(params.CashAddrPrefix(), data);
     }