diff --git a/src/bench/chacha_poly_aead.cpp b/src/bench/chacha_poly_aead.cpp
--- a/src/bench/chacha_poly_aead.cpp
+++ b/src/bench/chacha_poly_aead.cpp
@@ -96,7 +96,7 @@
     uint8_t hash[CHash256::OUTPUT_SIZE];
     std::vector<uint8_t> in(buffersize, 0);
     while (state.KeepRunning()) {
-        CHash256().Write(in.data(), in.size()).Finalize(hash);
+        CHash256().Write(in).Finalize(hash);
     }
 }
 
diff --git a/src/blockfilter.cpp b/src/blockfilter.cpp
--- a/src/blockfilter.cpp
+++ b/src/blockfilter.cpp
@@ -289,7 +289,7 @@
     const std::vector<uint8_t> &data = GetEncodedFilter();
 
     uint256 result;
-    CHash256().Write(data.data(), data.size()).Finalize(result.begin());
+    CHash256().Write(data).Finalize(result.begin());
     return result;
 }
 
@@ -297,9 +297,6 @@
     const uint256 &filter_hash = GetHash();
 
     uint256 result;
-    CHash256()
-        .Write(filter_hash.begin(), filter_hash.size())
-        .Write(prev_header.begin(), prev_header.size())
-        .Finalize(result.begin());
+    CHash256().Write(filter_hash).Write(prev_header).Finalize(result.begin());
     return result;
 }
diff --git a/src/hash.h b/src/hash.h
--- a/src/hash.h
+++ b/src/hash.h
@@ -32,8 +32,8 @@
         sha.Reset().Write(buf, CSHA256::OUTPUT_SIZE).Finalize(hash);
     }
 
-    CHash256 &Write(const uint8_t *data, size_t len) {
-        sha.Write(data, len);
+    CHash256 &Write(Span<const uint8_t> input) {
+        sha.Write(input.data(), input.size());
         return *this;
     }
 
@@ -57,8 +57,8 @@
         CRIPEMD160().Write(buf, CSHA256::OUTPUT_SIZE).Finalize(hash);
     }
 
-    CHash160 &Write(const uint8_t *data, size_t len) {
-        sha.Write(data, len);
+    CHash160 &Write(Span<const uint8_t> input) {
+        sha.Write(input.data(), input.size());
         return *this;
     }
 
@@ -73,8 +73,8 @@
     static const uint8_t pblank[1] = {};
     uint256 result;
     CHash256()
-        .Write(pbegin == pend ? pblank : (const uint8_t *)&pbegin[0],
-               (pend - pbegin) * sizeof(pbegin[0]))
+        .Write({pbegin == pend ? pblank : (const uint8_t *)&pbegin[0],
+                (pend - pbegin) * sizeof(pbegin[0])})
         .Finalize((uint8_t *)&result);
     return result;
 }
@@ -86,10 +86,10 @@
     static const uint8_t pblank[1] = {};
     uint256 result;
     CHash256()
-        .Write(p1begin == p1end ? pblank : (const uint8_t *)&p1begin[0],
-               (p1end - p1begin) * sizeof(p1begin[0]))
-        .Write(p2begin == p2end ? pblank : (const uint8_t *)&p2begin[0],
-               (p2end - p2begin) * sizeof(p2begin[0]))
+        .Write({p1begin == p1end ? pblank : (const uint8_t *)&p1begin[0],
+                (p1end - p1begin) * sizeof(p1begin[0])})
+        .Write({p2begin == p2end ? pblank : (const uint8_t *)&p2begin[0],
+                (p2end - p2begin) * sizeof(p2begin[0])})
         .Finalize((uint8_t *)&result);
     return result;
 }
@@ -99,8 +99,8 @@
     static uint8_t pblank[1] = {};
     uint160 result;
     CHash160()
-        .Write(pbegin == pend ? pblank : (const uint8_t *)&pbegin[0],
-               (pend - pbegin) * sizeof(pbegin[0]))
+        .Write({pbegin == pend ? pblank : (const uint8_t *)&pbegin[0],
+                (pend - pbegin) * sizeof(pbegin[0])})
         .Finalize((uint8_t *)&result);
     return result;
 }
@@ -132,7 +132,7 @@
     int GetVersion() const { return nVersion; }
 
     void write(const char *pch, size_t size) {
-        ctx.Write((const uint8_t *)pch, size);
+        ctx.Write({(const uint8_t *)pch, size});
     }
 
     // invalidates the object
diff --git a/src/key.cpp b/src/key.cpp
--- a/src/key.cpp
+++ b/src/key.cpp
@@ -308,10 +308,7 @@
     std::string str = "Bitcoin key verification\n";
     GetRandBytes(rnd, sizeof(rnd));
     uint256 hash;
-    CHash256()
-        .Write((uint8_t *)str.data(), str.size())
-        .Write(rnd, sizeof(rnd))
-        .Finalize(hash.begin());
+    CHash256().Write(MakeUCharSpan(str)).Write(rnd).Finalize(hash.begin());
     std::vector<uint8_t> vchSig;
     SignECDSA(hash, vchSig);
     return pubkey.VerifyECDSA(hash, vchSig);
diff --git a/src/net.cpp b/src/net.cpp
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -716,7 +716,7 @@
         vRecv.resize(std::min(hdr.nMessageSize, nDataPos + nCopy + 256 * 1024));
     }
 
-    hasher.Write((const uint8_t *)pch, nCopy);
+    hasher.Write({(const uint8_t *)pch, nCopy});
     memcpy(&vRecv[nDataPos], pch, nCopy);
     nDataPos += nCopy;
 
diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp
--- a/src/script/interpreter.cpp
+++ b/src/script/interpreter.cpp
@@ -940,13 +940,9 @@
                                 .Write(vch.data(), vch.size())
                                 .Finalize(vchHash.data());
                         } else if (opcode == OP_HASH160) {
-                            CHash160()
-                                .Write(vch.data(), vch.size())
-                                .Finalize(vchHash.data());
+                            CHash160().Write(vch).Finalize(vchHash.data());
                         } else if (opcode == OP_HASH256) {
-                            CHash256()
-                                .Write(vch.data(), vch.size())
-                                .Finalize(vchHash.data());
+                            CHash256().Write(vch).Finalize(vchHash.data());
                         }
                         popstack(stack);
                         stack.push_back(vchHash);
diff --git a/src/test/crypto_tests.cpp b/src/test/crypto_tests.cpp
--- a/src/test/crypto_tests.cpp
+++ b/src/test/crypto_tests.cpp
@@ -1063,7 +1063,7 @@
             in[j] = InsecureRandBits(8);
         }
         for (int j = 0; j < i; ++j) {
-            CHash256().Write(in + 64 * j, 64).Finalize(out1 + 32 * j);
+            CHash256().Write({in + 64 * j, 64}).Finalize(out1 + 32 * j);
         }
         SHA256D64(out2, in, i);
         BOOST_CHECK(memcmp(out1, out2, 32 * i) == 0);
diff --git a/src/test/fuzz/crypto.cpp b/src/test/fuzz/crypto.cpp
--- a/src/test/fuzz/crypto.cpp
+++ b/src/test/fuzz/crypto.cpp
@@ -51,8 +51,8 @@
                     }
                 }
 
-                (void)hash160.Write(data.data(), data.size());
-                (void)hash256.Write(data.data(), data.size());
+                (void)hash160.Write(data);
+                (void)hash256.Write(data);
                 (void)hmac_sha256.Write(data.data(), data.size());
                 (void)hmac_sha512.Write(data.data(), data.size());
                 (void)ripemd160.Write(data.data(), data.size());
diff --git a/src/test/key_tests.cpp b/src/test/key_tests.cpp
--- a/src/test/key_tests.cpp
+++ b/src/test/key_tests.cpp
@@ -379,10 +379,7 @@
     std::string str = "Bitcoin key verification\n";
     GetRandBytes(rnd, sizeof(rnd));
     uint256 hash;
-    CHash256()
-        .Write((uint8_t *)str.data(), str.size())
-        .Write(rnd, sizeof(rnd))
-        .Finalize(hash.begin());
+    CHash256().Write(MakeUCharSpan(str)).Write(rnd).Finalize(hash.begin());
 
     // import the static test key
     CKey key = DecodeSecret(strSecret1C);
diff --git a/src/test/merkle_tests.cpp b/src/test/merkle_tests.cpp
--- a/src/test/merkle_tests.cpp
+++ b/src/test/merkle_tests.cpp
@@ -79,10 +79,7 @@
                 }
             }
             mutated |= (inner[level] == h);
-            CHash256()
-                .Write(inner[level].begin(), 32)
-                .Write(h.begin(), 32)
-                .Finalize(h.begin());
+            CHash256().Write(inner[level]).Write(h).Finalize(h.begin());
         }
         // Store the resulting hash at inner position level.
         inner[level] = h;
@@ -108,10 +105,7 @@
         if (pbranch && matchh) {
             pbranch->push_back(h);
         }
-        CHash256()
-            .Write(h.begin(), 32)
-            .Write(h.begin(), 32)
-            .Finalize(h.begin());
+        CHash256().Write(h).Write(h).Finalize(h.begin());
         // Increment count to the value it would have if two entries at this
         // level had existed.
         count += (((uint32_t)1) << level);
@@ -126,10 +120,7 @@
                     matchh = true;
                 }
             }
-            CHash256()
-                .Write(inner[level].begin(), 32)
-                .Write(h.begin(), 32)
-                .Finalize(h.begin());
+            CHash256().Write(inner[level]).Write(h).Finalize(h.begin());
             level++;
         }
     }
diff --git a/src/test/settings_tests.cpp b/src/test/settings_tests.cpp
--- a/src/test/settings_tests.cpp
+++ b/src/test/settings_tests.cpp
@@ -255,7 +255,7 @@
         }
         desc += "\n";
 
-        out_sha.Write((const uint8_t *)desc.data(), desc.size());
+        out_sha.Write(MakeUCharSpan(desc));
         if (out_file) {
             BOOST_REQUIRE(fwrite(desc.data(), 1, desc.size(), out_file) ==
                           desc.size());
diff --git a/src/test/util_tests.cpp b/src/test/util_tests.cpp
--- a/src/test/util_tests.cpp
+++ b/src/test/util_tests.cpp
@@ -1177,7 +1177,7 @@
 
         desc += "\n";
 
-        out_sha.Write((const uint8_t *)desc.data(), desc.size());
+        out_sha.Write(MakeUCharSpan(desc));
         if (out_file) {
             BOOST_REQUIRE(fwrite(desc.data(), 1, desc.size(), out_file) ==
                           desc.size());
@@ -1318,7 +1318,7 @@
         }
         desc += "\n";
 
-        out_sha.Write((const uint8_t *)desc.data(), desc.size());
+        out_sha.Write(MakeUCharSpan(desc));
         if (out_file) {
             BOOST_REQUIRE(fwrite(desc.data(), 1, desc.size(), out_file) ==
                           desc.size());