diff --git a/perl/lib/Nix/Store.xs b/perl/lib/Nix/Store.xs
index 890310b3e80fc5af3d7a10cc7dfdf7af257a8d34..945ed49c75432041fa59a7ee704a0d8a241a49db 100644
--- a/perl/lib/Nix/Store.xs
+++ b/perl/lib/Nix/Store.xs
@@ -80,7 +80,7 @@ SV * queryReferences(char * path)
 SV * queryPathHash(char * path)
     PPCODE:
         try {
-            auto s = store()->queryPathInfo(store()->parseStorePath(path))->narHash.to_string();
+            auto s = store()->queryPathInfo(store()->parseStorePath(path))->narHash.to_string(Base32, true);
             XPUSHs(sv_2mortal(newSVpv(s.c_str(), 0)));
         } catch (Error & e) {
             croak("%s", e.what());
@@ -106,7 +106,7 @@ SV * queryPathInfo(char * path, int base32)
                 XPUSHs(&PL_sv_undef);
             else
                 XPUSHs(sv_2mortal(newSVpv(store()->printStorePath(*info->deriver).c_str(), 0)));
-            auto s = info->narHash.to_string(base32 ? Base32 : Base16);
+            auto s = info->narHash.to_string(base32 ? Base32 : Base16, true);
             XPUSHs(sv_2mortal(newSVpv(s.c_str(), 0)));
             mXPUSHi(info->registrationTime);
             mXPUSHi(info->narSize);
diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index c5a0d988683723f7f72bb433f81a18a997afce64..b9040879879cc37cdcd8a3d91a53ccdea5c074f3 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -23,7 +23,7 @@ void emitTreeAttrs(
 
     assert(tree.info.narHash);
     mkString(*state.allocAttr(v, state.symbols.create("narHash")),
-        tree.info.narHash.to_string(SRI));
+        tree.info.narHash.to_string(SRI, true));
 
     if (input->getRev()) {
         mkString(*state.allocAttr(v, state.symbols.create("rev")), input->getRev()->gitRev());
@@ -140,7 +140,7 @@ static void fetch(EvalState & state, const Pos & pos, Value * * args, Value & v,
             : hashFile(htSHA256, path);
         if (hash != *expectedHash)
             throw Error((unsigned int) 102, "hash mismatch in file downloaded from '%s':\n  wanted: %s\n  got:    %s",
-                *url, expectedHash->to_string(), hash.to_string());
+                *url, expectedHash->to_string(Base32, true), hash.to_string(Base32, true));
     }
 
     if (state.allowedPaths)
diff --git a/src/libfetchers/fetchers.cc b/src/libfetchers/fetchers.cc
index 94ac30e380042f09fa377925494f0e8899f1a624..ca555114da122f46ce8796cd4e21ae4587419dca 100644
--- a/src/libfetchers/fetchers.cc
+++ b/src/libfetchers/fetchers.cc
@@ -47,7 +47,7 @@ Attrs Input::toAttrs() const
 {
     auto attrs = toAttrsInternal();
     if (narHash)
-        attrs.emplace("narHash", narHash->to_string(SRI));
+        attrs.emplace("narHash", narHash->to_string(SRI, true));
     attrs.emplace("type", type());
     return attrs;
 }
@@ -67,7 +67,7 @@ std::pair<Tree, std::shared_ptr<const Input>> Input::fetchTree(ref<Store> store)
 
     if (narHash && narHash != input->narHash)
         throw Error("NAR hash mismatch in input '%s' (%s), expected '%s', got '%s'",
-            to_string(), tree.actualPath, narHash->to_string(SRI), input->narHash->to_string(SRI));
+            to_string(), tree.actualPath, narHash->to_string(SRI, true), input->narHash->to_string(SRI, true));
 
     return {std::move(tree), input};
 }
diff --git a/src/libfetchers/tarball.cc b/src/libfetchers/tarball.cc
index b6e57379bd03753ec2a7cd0f606434e01b1fe14a..1b0eba18a0872fc82293f9eb9c30e0fc681830ab 100644
--- a/src/libfetchers/tarball.cc
+++ b/src/libfetchers/tarball.cc
@@ -196,9 +196,9 @@ struct TarballInput : Input
         // NAR hashes are preferred over file hashes since tar/zip files
         // don't have a canonical representation.
         if (narHash)
-            url2.query.insert_or_assign("narHash", narHash->to_string(SRI));
+            url2.query.insert_or_assign("narHash", narHash->to_string(SRI, true));
         else if (hash)
-            url2.query.insert_or_assign("hash", hash->to_string(SRI));
+            url2.query.insert_or_assign("hash", hash->to_string(SRI, true));
         return url2;
     }
 
@@ -207,7 +207,7 @@ struct TarballInput : Input
         Attrs attrs;
         attrs.emplace("url", url.to_string());
         if (hash)
-            attrs.emplace("hash", hash->to_string(SRI));
+            attrs.emplace("hash", hash->to_string(SRI, true));
         return attrs;
     }
 
diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index f5c132a83977d67b807fd5e7437649d9dbfa919c..9582a90075852e3988b7a81166ee1922fa1664b1 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -3718,7 +3718,7 @@ void DerivationGoal::registerOutputs()
                 worker.hashMismatch = true;
                 delayedException = std::make_exception_ptr(
                     BuildError("hash mismatch in fixed-output derivation '%s':\n  wanted: %s\n  got:    %s",
-                        worker.store.printStorePath(dest), h.to_string(SRI), h2.to_string(SRI)));
+                        worker.store.printStorePath(dest), h.to_string(SRI, true), h2.to_string(SRI, true)));
 
                 Path actualDest = worker.store.Store::toRealPath(dest);
 
diff --git a/src/libstore/export-import.cc b/src/libstore/export-import.cc
index f0d01a2404371916a2637c086cc28dfe77ab28b2..54471d4a3b14b529a9b53ffc6dace46f7840da11 100644
--- a/src/libstore/export-import.cc
+++ b/src/libstore/export-import.cc
@@ -57,7 +57,7 @@ void Store::exportPath(const StorePath & path, Sink & sink)
     Hash hash = hashAndWriteSink.currentHash();
     if (hash != info->narHash && info->narHash != Hash(info->narHash.type))
         throw Error("hash of path '%s' has changed from '%s' to '%s'!",
-            printStorePath(path), info->narHash.to_string(), hash.to_string());
+            printStorePath(path), info->narHash.to_string(Base32, true), hash.to_string(Base32, true));
 
     hashAndWriteSink
         << exportMagic
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 80851b5910627f352e62ed763f646533edc48b71..1c3795eb1c0e7508fb964bb26221c17c67ebe173 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -580,7 +580,7 @@ uint64_t LocalStore::addValidPath(State & state,
 
     state.stmtRegisterValidPath.use()
         (printStorePath(info.path))
-        (info.narHash.to_string(Base16))
+        (info.narHash.to_string(Base16, true))
         (info.registrationTime == 0 ? time(0) : info.registrationTime)
         (info.deriver ? printStorePath(*info.deriver) : "", (bool) info.deriver)
         (info.narSize, info.narSize != 0)
@@ -680,7 +680,7 @@ void LocalStore::updatePathInfo(State & state, const ValidPathInfo & info)
 {
     state.stmtUpdatePathInfo.use()
         (info.narSize, info.narSize != 0)
-        (info.narHash.to_string(Base16))
+        (info.narHash.to_string(Base16, true))
         (info.ultimate ? 1 : 0, info.ultimate)
         (concatStringsSep(" ", info.sigs), !info.sigs.empty())
         (info.ca, !info.ca.empty())
@@ -1022,7 +1022,7 @@ void LocalStore::addToStore(const ValidPathInfo & info, Source & source,
 
             if (hashResult.first != info.narHash)
                 throw Error("hash mismatch importing path '%s';\n  wanted: %s\n  got:    %s",
-                    printStorePath(info.path), info.narHash.to_string(), hashResult.first.to_string());
+                    printStorePath(info.path), info.narHash.to_string(Base32, true), hashResult.first.to_string(Base32, true));
 
             if (hashResult.second != info.narSize)
                 throw Error("size mismatch importing path '%s';\n  wanted: %s\n  got:   %s",
@@ -1155,7 +1155,7 @@ StorePath LocalStore::addTextToStore(const string & name, const string & s,
             info.narHash = narHash;
             info.narSize = sink.s->size();
             info.references = cloneStorePathSet(references);
-            info.ca = "text:" + hash.to_string();
+            info.ca = "text:" + hash.to_string(Base32, true);
             registerValidPath(info);
         }
 
@@ -1273,7 +1273,7 @@ bool LocalStore::verifyStore(bool checkContents, RepairFlag repair)
 
                 if (info->narHash != nullHash && info->narHash != current.first) {
                     printError("path '%s' was modified! expected hash '%s', got '%s'",
-                        printStorePath(i), info->narHash.to_string(), current.first.to_string());
+                        printStorePath(i), info->narHash.to_string(Base32, true), current.first.to_string(Base32, true));
                     if (repair) repairPath(i); else errors = true;
                 } else {
 
diff --git a/src/libstore/nar-info-disk-cache.cc b/src/libstore/nar-info-disk-cache.cc
index 442541330a2d0c815e1d5fd88fb0e18a3ec4d23a..e8cf1d17724e2489315fa00c8bc7e77dee2658a0 100644
--- a/src/libstore/nar-info-disk-cache.cc
+++ b/src/libstore/nar-info-disk-cache.cc
@@ -230,9 +230,9 @@ public:
                     (std::string(info->path.name()))
                     (narInfo ? narInfo->url : "", narInfo != 0)
                     (narInfo ? narInfo->compression : "", narInfo != 0)
-                    (narInfo && narInfo->fileHash ? narInfo->fileHash.to_string() : "", narInfo && narInfo->fileHash)
+                    (narInfo && narInfo->fileHash ? narInfo->fileHash.to_string(Base32, true) : "", narInfo && narInfo->fileHash)
                     (narInfo ? narInfo->fileSize : 0, narInfo != 0 && narInfo->fileSize)
-                    (info->narHash.to_string())
+                    (info->narHash.to_string(Base32, true))
                     (info->narSize)
                     (concatStringsSep(" ", info->shortRefs()))
                     (info->deriver ? std::string(info->deriver->to_string()) : "", (bool) info->deriver)
diff --git a/src/libstore/nar-info.cc b/src/libstore/nar-info.cc
index 1375094b5bf14daee336d23e10779eaa269cf157..6b16be08a1310fc3e683baa47cad7d1c6f727cab 100644
--- a/src/libstore/nar-info.cc
+++ b/src/libstore/nar-info.cc
@@ -87,10 +87,10 @@ std::string NarInfo::to_string(const Store & store) const
     assert(compression != "");
     res += "Compression: " + compression + "\n";
     assert(fileHash.type == htSHA256);
-    res += "FileHash: " + fileHash.to_string(Base32) + "\n";
+    res += "FileHash: " + fileHash.to_string(Base32, true) + "\n";
     res += "FileSize: " + std::to_string(fileSize) + "\n";
     assert(narHash.type == htSHA256);
-    res += "NarHash: " + narHash.to_string(Base32) + "\n";
+    res += "NarHash: " + narHash.to_string(Base32, true) + "\n";
     res += "NarSize: " + std::to_string(narSize) + "\n";
 
     res += "References: " + concatStringsSep(" ", shortRefs()) + "\n";
diff --git a/src/libstore/optimise-store.cc b/src/libstore/optimise-store.cc
index 8ac382e9dbf3c2b644b77f1acfd5fa3f8a71375b..3f4b72b9c923b080321f4ca7b9bfc999483e1eee 100644
--- a/src/libstore/optimise-store.cc
+++ b/src/libstore/optimise-store.cc
@@ -150,7 +150,7 @@ void LocalStore::optimisePath_(Activity * act, OptimiseStats & stats,
        contents of the symlink (i.e. the result of readlink()), not
        the contents of the target (which may not even exist). */
     Hash hash = hashPath(htSHA256, path).first;
-    debug(format("'%1%' has hash '%2%'") % path % hash.to_string());
+    debug(format("'%1%' has hash '%2%'") % path % hash.to_string(Base32, true));
 
     /* Check if this is a known hash. */
     Path linkPath = linksDir + "/" + hash.to_string(Base32, false);
diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index 095363d0c9b8f9a8fd2144a203e7620c1e5030a2..0645fca84160819c371f6c35f237ea4b63d74af7 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -142,7 +142,7 @@ StorePath Store::makeStorePath(const string & type,
     const Hash & hash, std::string_view name) const
 {
     /* e.g., "source:sha256:1abc...:/nix/store:foo.tar.gz" */
-    string s = type + ":" + hash.to_string(Base16) + ":" + storeDir + ":" + std::string(name);
+    string s = type + ":" + hash.to_string(Base16, true) + ":" + storeDir + ":" + std::string(name);
     auto h = compressHash(hashString(htSHA256, s), 20);
     return StorePath::make(h.hash, name);
 }
@@ -186,7 +186,7 @@ StorePath Store::makeFixedOutputPath(
             hashString(htSHA256,
                 "fixed:out:"
                 + (recursive == FileIngestionMethod::Recursive ? (string) "r:" : "")
-                + hash.to_string(Base16) + ":"),
+                + hash.to_string(Base16, true) + ":"),
             name);
     }
 }
@@ -461,7 +461,7 @@ void Store::pathInfoToJSON(JSONPlaceholder & jsonOut, const StorePathSet & store
             auto info = queryPathInfo(storePath);
 
             jsonPath
-                .attr("narHash", info->narHash.to_string(hashBase))
+                .attr("narHash", info->narHash.to_string(hashBase, true))
                 .attr("narSize", info->narSize);
 
             {
@@ -504,7 +504,7 @@ void Store::pathInfoToJSON(JSONPlaceholder & jsonOut, const StorePathSet & store
                     if (!narInfo->url.empty())
                         jsonPath.attr("url", narInfo->url);
                     if (narInfo->fileHash)
-                        jsonPath.attr("downloadHash", narInfo->fileHash.to_string());
+                        jsonPath.attr("downloadHash", narInfo->fileHash.to_string(Base32, true));
                     if (narInfo->fileSize)
                         jsonPath.attr("downloadSize", narInfo->fileSize);
                     if (showClosureSize)
@@ -760,7 +760,7 @@ std::string ValidPathInfo::fingerprint(const Store & store) const
             store.printStorePath(path));
     return
         "1;" + store.printStorePath(path) + ";"
-        + narHash.to_string(Base32) + ";"
+        + narHash.to_string(Base32, true) + ";"
         + std::to_string(narSize) + ";"
         + concatStringsSep(",", store.printStorePathSet(references));
 }
@@ -836,7 +836,7 @@ std::string makeFixedOutputCA(FileIngestionMethod recursive, const Hash & hash)
 {
     return "fixed:"
         + (recursive == FileIngestionMethod::Recursive ? (std::string) "r:" : "")
-        + hash.to_string();
+        + hash.to_string(Base32, true);
 }
 
 
diff --git a/src/libutil/hash.hh b/src/libutil/hash.hh
index ea9fca3e74f2e0565d7a580928bf210be2609a21..4ff13f6b23a323d3f11d2158abf16c8b38ab2a56 100644
--- a/src/libutil/hash.hh
+++ b/src/libutil/hash.hh
@@ -79,7 +79,7 @@ struct Hash
     /* Return a string representation of the hash, in base-16, base-32
        or base-64. By default, this is prefixed by the hash type
        (e.g. "sha256:"). */
-    std::string to_string(Base base = Base32, bool includeType = true) const;
+    std::string to_string(Base base, bool includeType) const;
 
     std::string gitRev() const
     {
diff --git a/src/libutil/tests/hash.cc b/src/libutil/tests/hash.cc
index 7cb4398178a7a9df883a3e34408343ccfb3f666f..5334b046e5dd18f17c82ee993809b8d8f12c46d9 100644
--- a/src/libutil/tests/hash.cc
+++ b/src/libutil/tests/hash.cc
@@ -11,28 +11,28 @@ namespace nix {
         // values taken from: https://tools.ietf.org/html/rfc1321
         auto s1 = "";
         auto hash = hashString(HashType::htMD5, s1);
-        ASSERT_EQ(hash.to_string(Base::Base16), "md5:d41d8cd98f00b204e9800998ecf8427e");
+        ASSERT_EQ(hash.to_string(Base::Base16, true), "md5:d41d8cd98f00b204e9800998ecf8427e");
     }
 
     TEST(hashString, testKnownMD5Hashes2) {
         // values taken from: https://tools.ietf.org/html/rfc1321
         auto s2 = "abc";
         auto hash = hashString(HashType::htMD5, s2);
-        ASSERT_EQ(hash.to_string(Base::Base16), "md5:900150983cd24fb0d6963f7d28e17f72");
+        ASSERT_EQ(hash.to_string(Base::Base16, true), "md5:900150983cd24fb0d6963f7d28e17f72");
     }
 
     TEST(hashString, testKnownSHA1Hashes1) {
         // values taken from: https://tools.ietf.org/html/rfc3174
         auto s = "abc";
         auto hash = hashString(HashType::htSHA1, s);
-        ASSERT_EQ(hash.to_string(Base::Base16),"sha1:a9993e364706816aba3e25717850c26c9cd0d89d");
+        ASSERT_EQ(hash.to_string(Base::Base16, true),"sha1:a9993e364706816aba3e25717850c26c9cd0d89d");
     }
 
     TEST(hashString, testKnownSHA1Hashes2) {
         // values taken from: https://tools.ietf.org/html/rfc3174
         auto s = "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq";
         auto hash = hashString(HashType::htSHA1, s);
-        ASSERT_EQ(hash.to_string(Base::Base16),"sha1:84983e441c3bd26ebaae4aa1f95129e5e54670f1");
+        ASSERT_EQ(hash.to_string(Base::Base16, true),"sha1:84983e441c3bd26ebaae4aa1f95129e5e54670f1");
     }
 
     TEST(hashString, testKnownSHA256Hashes1) {
@@ -40,7 +40,7 @@ namespace nix {
         auto s = "abc";
 
         auto hash = hashString(HashType::htSHA256, s);
-        ASSERT_EQ(hash.to_string(Base::Base16),
+        ASSERT_EQ(hash.to_string(Base::Base16, true),
                 "sha256:ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad");
     }
 
@@ -48,7 +48,7 @@ namespace nix {
         // values taken from: https://tools.ietf.org/html/rfc4634
         auto s = "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq";
         auto hash = hashString(HashType::htSHA256, s);
-        ASSERT_EQ(hash.to_string(Base::Base16),
+        ASSERT_EQ(hash.to_string(Base::Base16, true),
                 "sha256:248d6a61d20638b8e5c026930c3e6039a33ce45964ff2167f6ecedd419db06c1");
     }
 
@@ -56,7 +56,7 @@ namespace nix {
         // values taken from: https://tools.ietf.org/html/rfc4634
         auto s = "abc";
         auto hash = hashString(HashType::htSHA512, s);
-        ASSERT_EQ(hash.to_string(Base::Base16),
+        ASSERT_EQ(hash.to_string(Base::Base16, true),
                 "sha512:ddaf35a193617abacc417349ae20413112e6fa4e89a9"
                 "7ea20a9eeee64b55d39a2192992a274fc1a836ba3c23a3feebbd"
                 "454d4423643ce80e2a9ac94fa54ca49f");
@@ -67,7 +67,7 @@ namespace nix {
         auto s = "abcdefghbcdefghicdefghijdefghijkefghijklfghijklmghijklmnhijklmnoijklmnopjklmnopqklmnopqrlmnopqrsmnopqrstnopqrstu";
 
         auto hash = hashString(HashType::htSHA512, s);
-        ASSERT_EQ(hash.to_string(Base::Base16),
+        ASSERT_EQ(hash.to_string(Base::Base16, true),
                 "sha512:8e959b75dae313da8cf4f72814fc143f8f7779c6eb9f7fa1"
                 "7299aeadb6889018501d289e4900f7e4331b99dec4b5433a"
                 "c7d329eeb6dd26545e96e55b874be909");
diff --git a/src/nix-store/nix-store.cc b/src/nix-store/nix-store.cc
index 3a3060ad82d8f3c1947c64d4c431dc4755bd28d9..9491a0c26a1e3cf232f4e53089da24b93fd45aaf 100644
--- a/src/nix-store/nix-store.cc
+++ b/src/nix-store/nix-store.cc
@@ -373,7 +373,7 @@ static void opQuery(Strings opFlags, Strings opArgs)
                     auto info = store->queryPathInfo(j);
                     if (query == qHash) {
                         assert(info->narHash.type == htSHA256);
-                        cout << fmt("%s\n", info->narHash.to_string(Base32));
+                        cout << fmt("%s\n", info->narHash.to_string(Base32, true));
                     } else if (query == qSize)
                         cout << fmt("%d\n", info->narSize);
                 }
@@ -728,7 +728,7 @@ static void opVerifyPath(Strings opFlags, Strings opArgs)
         if (current.first != info->narHash) {
             printError(
                 "path '%s' was modified! expected hash '%s', got '%s'",
-                store->printStorePath(path), info->narHash.to_string(), current.first.to_string());
+                store->printStorePath(path), info->narHash.to_string(Base32, true), current.first.to_string(Base32, true));
             status = 1;
         }
     }
@@ -856,7 +856,7 @@ static void opServe(Strings opFlags, Strings opArgs)
                         out << info->narSize // downloadSize
                             << info->narSize;
                         if (GET_PROTOCOL_MINOR(clientVersion) >= 4)
-                            out << (info->narHash ? info->narHash.to_string() : "") << info->ca << info->sigs;
+                            out << (info->narHash ? info->narHash.to_string(Base32, true) : "") << info->ca << info->sigs;
                     } catch (InvalidPath &) {
                     }
                 }
diff --git a/src/nix/verify.cc b/src/nix/verify.cc
index cf1fa6a990c80fb1319818c8d2935afd898e1d52..287dad1012388f4d45e186e3925d6bfe1adac652 100644
--- a/src/nix/verify.cc
+++ b/src/nix/verify.cc
@@ -101,7 +101,7 @@ struct CmdVerify : StorePathsCommand
                         act2.result(resCorruptedPath, store->printStorePath(info->path));
                         printError(
                             "path '%s' was modified! expected hash '%s', got '%s'",
-                            store->printStorePath(info->path), info->narHash.to_string(), hash.first.to_string());
+                            store->printStorePath(info->path), info->narHash.to_string(Base32, true), hash.first.to_string(Base32, true));
                     }
 
                 }