diff --git a/src/backend/BackendFactory.h b/src/backend/BackendFactory.h
index 427d4c63..382ec3f5 100644
--- a/src/backend/BackendFactory.h
+++ b/src/backend/BackendFactory.h
@@ -1,5 +1,4 @@
-#ifndef RIPPLE_APP_REPORTING_BACKENDFACTORY_H_INCLUDED
-#define RIPPLE_APP_REPORTING_BACKENDFACTORY_H_INCLUDED
+#pragma once
 
 #include <backend/BackendInterface.h>
 #include <backend/CassandraBackend.h>
@@ -42,5 +41,3 @@ make_Backend(boost::asio::io_context& ioc, clio::Config const& config)
     return backend;
 }
 }  // namespace Backend
-
-#endif  // RIPPLE_REPORTING_BACKEND_FACTORY
diff --git a/src/backend/BackendInterface.h b/src/backend/BackendInterface.h
index 1a36b6c4..f50c94e6 100644
--- a/src/backend/BackendInterface.h
+++ b/src/backend/BackendInterface.h
@@ -1,5 +1,4 @@
-#ifndef RIPPLE_APP_REPORTING_BACKENDINTERFACE_H_INCLUDED
-#define RIPPLE_APP_REPORTING_BACKENDINTERFACE_H_INCLUDED
+#pragma once
 
 #include <ripple/ledger/ReadView.h>
 #include <backend/DBHelpers.h>
@@ -643,4 +642,3 @@ private:
 
 }  // namespace Backend
 using BackendInterface = Backend::BackendInterface;
-#endif
diff --git a/src/backend/CassandraBackend.h b/src/backend/CassandraBackend.h
index 085da9b4..efa71f36 100644
--- a/src/backend/CassandraBackend.h
+++ b/src/backend/CassandraBackend.h
@@ -1,5 +1,4 @@
-#ifndef RIPPLE_APP_REPORTING_CASSANDRABACKEND_H_INCLUDED
-#define RIPPLE_APP_REPORTING_CASSANDRABACKEND_H_INCLUDED
+#pragma once
 
 #include <ripple/basics/base_uint.h>
 #include <backend/BackendInterface.h>
@@ -1258,4 +1257,3 @@ public:
 };
 
 }  // namespace Backend
-#endif
diff --git a/src/backend/DBHelpers.h b/src/backend/DBHelpers.h
index 11ba2489..6642bf09 100644
--- a/src/backend/DBHelpers.h
+++ b/src/backend/DBHelpers.h
@@ -1,5 +1,4 @@
-#ifndef CLIO_BACKEND_DBHELPERS_H_INCLUDED
-#define CLIO_BACKEND_DBHELPERS_H_INCLUDED
+#pragma once
 
 #include <ripple/basics/Log.h>
 #include <ripple/basics/StringUtilities.h>
@@ -181,4 +180,3 @@ uint256ToString(ripple::uint256 const& uint)
 }
 
 static constexpr std::uint32_t rippleEpochStart = 946684800;
-#endif
diff --git a/src/backend/SimpleCache.h b/src/backend/SimpleCache.h
index 5e17c424..7dc24174 100644
--- a/src/backend/SimpleCache.h
+++ b/src/backend/SimpleCache.h
@@ -1,5 +1,4 @@
-#ifndef CLIO_SIMPLECACHE_H_INCLUDED
-#define CLIO_SIMPLECACHE_H_INCLUDED
+#pragma once
 
 #include <ripple/basics/base_uint.h>
 #include <ripple/basics/hardened_hash.h>
@@ -78,4 +77,3 @@ public:
 };
 
 }  // namespace Backend
-#endif
diff --git a/src/backend/Types.h b/src/backend/Types.h
index b382e95e..c3f8b618 100644
--- a/src/backend/Types.h
+++ b/src/backend/Types.h
@@ -1,5 +1,5 @@
-#ifndef CLIO_TYPES_H_INCLUDED
-#define CLIO_TYPES_H_INCLUDED
+#pragma once
+
 #include <ripple/basics/base_uint.h>
 #include <ripple/protocol/AccountID.h>
 #include <optional>
@@ -89,4 +89,3 @@ constexpr ripple::uint256 lastKey{
 constexpr ripple::uint256 hi192{
     "0000000000000000000000000000000000000000000000001111111111111111"};
 }  // namespace Backend
-#endif
diff --git a/src/config/Config.h b/src/config/Config.h
index be1d6a7f..fb45f791 100644
--- a/src/config/Config.h
+++ b/src/config/Config.h
@@ -1,5 +1,4 @@
-#ifndef RIPPLE_APP_CONFIG_H_INCLUDED
-#define RIPPLE_APP_CONFIG_H_INCLUDED
+#pragma once
 
 #include <config/detail/Helpers.h>
 
@@ -385,5 +384,3 @@ public:
 };
 
 }  // namespace clio
-
-#endif  // RIPPLE_APP_CONFIG_H_INCLUDED
diff --git a/src/config/detail/Helpers.h b/src/config/detail/Helpers.h
index 81cd0ca1..143f5947 100644
--- a/src/config/detail/Helpers.h
+++ b/src/config/detail/Helpers.h
@@ -1,5 +1,4 @@
-#ifndef RIPPLE_APP_CONFIG_DETAIL_H_INCLUDED
-#define RIPPLE_APP_CONFIG_DETAIL_H_INCLUDED
+#pragma once
 
 #include <optional>
 #include <queue>
@@ -144,5 +143,3 @@ typeName<double>()
 }
 
 };  // namespace clio::detail
-
-#endif  // RIPPLE_APP_CONFIG_DETAIL_H_INCLUDED
diff --git a/src/etl/ETLHelpers.h b/src/etl/ETLHelpers.h
index d50709af..fce4584f 100644
--- a/src/etl/ETLHelpers.h
+++ b/src/etl/ETLHelpers.h
@@ -1,5 +1,5 @@
-#ifndef RIPPLE_APP_REPORTING_ETLHELPERS_H_INCLUDED
-#define RIPPLE_APP_REPORTING_ETLHELPERS_H_INCLUDED
+#pragma once
+
 #include <ripple/basics/base_uint.h>
 #include <condition_variable>
 #include <mutex>
@@ -171,5 +171,3 @@ getMarkers(size_t numMarkers)
     }
     return markers;
 }
-
-#endif  // RIPPLE_APP_REPORTING_ETLHELPERS_H_INCLUDED
diff --git a/src/etl/ETLSource.h b/src/etl/ETLSource.h
index f877c930..449009fc 100644
--- a/src/etl/ETLSource.h
+++ b/src/etl/ETLSource.h
@@ -1,5 +1,4 @@
-#ifndef RIPPLE_APP_REPORTING_ETLSOURCE_H_INCLUDED
-#define RIPPLE_APP_REPORTING_ETLSOURCE_H_INCLUDED
+#pragma once
 
 #include <backend/BackendInterface.h>
 #include <config/Config.h>
@@ -704,5 +703,3 @@ private:
     bool
     execute(Func f, uint32_t ledgerSequence);
 };
-
-#endif
diff --git a/src/etl/ProbingETLSource.h b/src/etl/ProbingETLSource.h
index 3eaf6a04..9ac0c2ba 100644
--- a/src/etl/ProbingETLSource.h
+++ b/src/etl/ProbingETLSource.h
@@ -1,5 +1,4 @@
-#ifndef RIPPLE_APP_REPORTING_PROBINGETLSOURCE_H_INCLUDED
-#define RIPPLE_APP_REPORTING_PROBINGETLSOURCE_H_INCLUDED
+#pragma once
 
 #include <boost/asio.hpp>
 #include <boost/beast/core.hpp>
@@ -92,5 +91,3 @@ private:
     ETLSourceHooks
     make_PlainHooks() noexcept;
 };
-
-#endif
diff --git a/src/etl/ReportingETL.h b/src/etl/ReportingETL.h
index e5e479d1..222b73a6 100644
--- a/src/etl/ReportingETL.h
+++ b/src/etl/ReportingETL.h
@@ -1,5 +1,4 @@
-#ifndef RIPPLE_APP_REPORTING_REPORTINGETL_H_INCLUDED
-#define RIPPLE_APP_REPORTING_REPORTINGETL_H_INCLUDED
+#pragma once
 
 #include <ripple/ledger/ReadView.h>
 #include <boost/algorithm/string.hpp>
@@ -395,5 +394,3 @@ public:
         return now - (rippleEpochStart + closeTime);
     }
 };
-
-#endif
diff --git a/src/log/Logger.h b/src/log/Logger.h
index 1b81a824..5da6c9a1 100644
--- a/src/log/Logger.h
+++ b/src/log/Logger.h
@@ -1,5 +1,4 @@
-#ifndef RIPPLE_UTIL_LOGGER_H
-#define RIPPLE_UTIL_LOGGER_H
+#pragma once
 
 #include <boost/algorithm/string/predicate.hpp>
 #include <boost/filesystem.hpp>
@@ -253,5 +252,3 @@ public:
 };
 
 };  // namespace clio
-
-#endif  // RIPPLE_UTIL_LOGGER_H
diff --git a/src/main/Build.h b/src/main/Build.h
index fb581901..525d5ce8 100644
--- a/src/main/Build.h
+++ b/src/main/Build.h
@@ -1,5 +1,4 @@
-#ifndef CLIO_BUILD_INFO_H
-#define CLIO_BUILD_INFO_H
+#pragma once
 
 #include <string>
 
@@ -12,5 +11,3 @@ std::string const&
 getClioFullVersionString();
 
 }  // namespace Build
-
-#endif  // CLIO_BUILD_INFO_H
diff --git a/src/rpc/Counters.h b/src/rpc/Counters.h
index 66943acc..74ebbe7c 100644
--- a/src/rpc/Counters.h
+++ b/src/rpc/Counters.h
@@ -1,5 +1,4 @@
-#ifndef RPC_COUNTERS_H
-#define RPC_COUNTERS_H
+#pragma once
 
 #include <boost/json.hpp>
 #include <chrono>
@@ -53,5 +52,3 @@ public:
 };
 
 }  // namespace RPC
-
-#endif  // RPC_COUNTERS_H
diff --git a/src/rpc/Errors.h b/src/rpc/Errors.h
index 75edc218..e53df699 100644
--- a/src/rpc/Errors.h
+++ b/src/rpc/Errors.h
@@ -1,5 +1,4 @@
-#ifndef REPORTING_RPC_ERRORS_H_INCLUDED
-#define REPORTING_RPC_ERRORS_H_INCLUDED
+#pragma once
 
 #include <ripple/protocol/ErrorCodes.h>
 
@@ -236,5 +235,3 @@ makeError(
     std::optional<std::string_view> customMessage = std::nullopt);
 
 }  // namespace RPC
-
-#endif  // REPORTING_RPC_ERRORS_H_INCLUDED
diff --git a/src/rpc/Handlers.h b/src/rpc/Handlers.h
index e84ec391..fd7937cf 100644
--- a/src/rpc/Handlers.h
+++ b/src/rpc/Handlers.h
@@ -1,5 +1,4 @@
-#ifndef REPORTING_HANDLERS_H_INCLUDED
-#define REPORTING_HANDLERS_H_INCLUDED
+#pragma once
 
 #include <rpc/RPC.h>
 
@@ -102,4 +101,3 @@ doServerInfo(Context const& context);
 Result
 doRandom(Context const& context);
 }  // namespace RPC
-#endif
diff --git a/src/rpc/RPC.h b/src/rpc/RPC.h
index d595f835..078f7b3b 100644
--- a/src/rpc/RPC.h
+++ b/src/rpc/RPC.h
@@ -1,5 +1,4 @@
-#ifndef REPORTING_RPC_H_INCLUDED
-#define REPORTING_RPC_H_INCLUDED
+#pragma once
 
 #include <backend/BackendInterface.h>
 #include <log/Logger.h>
@@ -146,5 +145,3 @@ logDuration(Context const& ctx, T const& dur)
 }
 
 }  // namespace RPC
-
-#endif  // REPORTING_RPC_H_INCLUDED
diff --git a/src/rpc/RPCHelpers.h b/src/rpc/RPCHelpers.h
index 5ebf864e..05beef5f 100644
--- a/src/rpc/RPCHelpers.h
+++ b/src/rpc/RPCHelpers.h
@@ -1,6 +1,5 @@
+#pragma once
 
-#ifndef XRPL_REPORTING_RPCHELPERS_H_INCLUDED
-#define XRPL_REPORTING_RPCHELPERS_H_INCLUDED
 /*
  * This file contains a variety of utility functions used when executing
  * the handlers
@@ -272,4 +271,3 @@ computeBookChanges(
     std::vector<Backend::TransactionAndMetadata> const& transactions);
 
 }  // namespace RPC
-#endif
diff --git a/src/rpc/WorkQueue.h b/src/rpc/WorkQueue.h
index c17634b8..35d0192c 100644
--- a/src/rpc/WorkQueue.h
+++ b/src/rpc/WorkQueue.h
@@ -1,5 +1,4 @@
-#ifndef CLIO_WORK_QUEUE_H
-#define CLIO_WORK_QUEUE_H
+#pragma once
 
 #include <log/Logger.h>
 
@@ -77,5 +76,3 @@ private:
     boost::asio::io_context ioc_ = {};
     std::optional<boost::asio::io_context::work> work_{ioc_};
 };
-
-#endif  // CLIO_WORK_QUEUE_H
diff --git a/src/subscriptions/Message.h b/src/subscriptions/Message.h
index 32c58b1d..20e271d7 100644
--- a/src/subscriptions/Message.h
+++ b/src/subscriptions/Message.h
@@ -1,5 +1,4 @@
-#ifndef CLIO_SUBSCRIPTION_MESSAGE_H
-#define CLIO_SUBSCRIPTION_MESSAGE_H
+#pragma once
 
 #include <string>
 
@@ -36,5 +35,3 @@ public:
         return message_.size();
     }
 };
-
-#endif  // CLIO_SUBSCRIPTION_MESSAGE_H
\ No newline at end of file
diff --git a/src/subscriptions/SubscriptionManager.h b/src/subscriptions/SubscriptionManager.h
index bcc268ed..1339d7ac 100644
--- a/src/subscriptions/SubscriptionManager.h
+++ b/src/subscriptions/SubscriptionManager.h
@@ -1,5 +1,4 @@
-#ifndef SUBSCRIPTION_MANAGER_H
-#define SUBSCRIPTION_MANAGER_H
+#pragma once
 
 #include <backend/BackendInterface.h>
 #include <config/Config.h>
@@ -285,5 +284,3 @@ private:
     std::unordered_map<session_ptr, std::vector<CleanupFunction>>
         cleanupFuncs_ = {};
 };
-
-#endif  // SUBSCRIPTION_MANAGER_H
diff --git a/src/util/Taggable.h b/src/util/Taggable.h
index 4eaf4c6f..74b7dbd7 100644
--- a/src/util/Taggable.h
+++ b/src/util/Taggable.h
@@ -1,5 +1,4 @@
-#ifndef RIPPLE_UTIL_TAGDECORATOR_H
-#define RIPPLE_UTIL_TAGDECORATOR_H
+#pragma once
 
 #include <boost/algorithm/string/predicate.hpp>
 #include <boost/json.hpp>
@@ -259,5 +258,3 @@ public:
 };
 
 }  // namespace util
-
-#endif  // RIPPLE_UTIL_TAGDECORATOR_H
diff --git a/src/webserver/DOSGuard.h b/src/webserver/DOSGuard.h
index e5ef2815..4ae34f58 100644
--- a/src/webserver/DOSGuard.h
+++ b/src/webserver/DOSGuard.h
@@ -1,5 +1,4 @@
-#ifndef RIPPLE_REPORTING_DOS_GUARD_H
-#define RIPPLE_REPORTING_DOS_GUARD_H
+#pragma once
 
 #include <boost/asio.hpp>
 #include <string>
@@ -100,4 +99,3 @@ private:
             boost::transform_iterator(std::end(whitelist), transform)};
     }
 };
-#endif
diff --git a/src/webserver/HttpBase.h b/src/webserver/HttpBase.h
index 4bb6a39a..0b62859b 100644
--- a/src/webserver/HttpBase.h
+++ b/src/webserver/HttpBase.h
@@ -1,5 +1,4 @@
-#ifndef RIPPLE_REPORTING_HTTP_BASE_SESSION_H
-#define RIPPLE_REPORTING_HTTP_BASE_SESSION_H
+#pragma once
 
 #include <boost/asio/dispatch.hpp>
 #include <boost/asio/spawn.hpp>
@@ -468,5 +467,3 @@ handle_request(
                 RPC::makeError(RPC::RippledError::rpcINTERNAL))));
     }
 }
-
-#endif  // RIPPLE_REPORTING_HTTP_BASE_SESSION_H
diff --git a/src/webserver/HttpSession.h b/src/webserver/HttpSession.h
index 9f57f132..ce3fe987 100644
--- a/src/webserver/HttpSession.h
+++ b/src/webserver/HttpSession.h
@@ -1,5 +1,4 @@
-#ifndef RIPPLE_REPORTING_HTTP_SESSION_H
-#define RIPPLE_REPORTING_HTTP_SESSION_H
+#pragma once
 
 #include <webserver/HttpBase.h>
 
@@ -91,5 +90,3 @@ public:
         // At this point the connection is closed gracefully
     }
 };
-
-#endif  // RIPPLE_REPORTING_HTTP_SESSION_H
diff --git a/src/webserver/Listener.h b/src/webserver/Listener.h
index 272fdb9e..1f479c3d 100644
--- a/src/webserver/Listener.h
+++ b/src/webserver/Listener.h
@@ -1,5 +1,4 @@
-#ifndef LISTENER_H
-#define LISTENER_H
+#pragma once
 
 #include <log/Logger.h>
 #include <subscriptions/SubscriptionManager.h>
@@ -369,5 +368,3 @@ make_HttpServer(
     return server;
 }
 }  // namespace Server
-
-#endif  // LISTENER_H
diff --git a/src/webserver/PlainWsSession.h b/src/webserver/PlainWsSession.h
index ffe58b48..62012ca6 100644
--- a/src/webserver/PlainWsSession.h
+++ b/src/webserver/PlainWsSession.h
@@ -1,5 +1,4 @@
-#ifndef RIPPLE_REPORTING_WS_SESSION_H
-#define RIPPLE_REPORTING_WS_SESSION_H
+#pragma once
 
 #include <boost/asio/dispatch.hpp>
 #include <boost/beast/core.hpp>
@@ -210,5 +209,3 @@ private:
             ->run(std::move(req_));
     }
 };
-
-#endif  // RIPPLE_REPORTING_WS_SESSION_H
diff --git a/src/webserver/Ssl.h b/src/webserver/Ssl.h
index fb842480..d97a1167 100644
--- a/src/webserver/Ssl.h
+++ b/src/webserver/Ssl.h
@@ -1,24 +1,4 @@
-//------------------------------------------------------------------------------
-/*
-    This file is part of rippled: https://github.com/ripple/rippled
-    Copyright (c) 2021 Ripple Labs Inc.
-
-    Permission to use, copy, modify, and/or distribute this software for any
-    purpose  with  or without fee is hereby granted, provided that the above
-    copyright notice and this permission notice appear in all copies.
-
-    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
-    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
-    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
-    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
-    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
-    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
-    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
-*/
-//==============================================================================
-
-#ifndef REPORTING_SSL_H
-#define REPORTING_SSL_H
+#pragma once
 
 #include <boost/asio/ssl.hpp>
 
@@ -62,5 +42,3 @@ parse_certs(const char* certFilename, const char* keyFilename)
 
     return ctx;
 }
-
-#endif  // REPORTING_SSL_H
\ No newline at end of file
diff --git a/src/webserver/SslHttpSession.h b/src/webserver/SslHttpSession.h
index b730d172..e25141e9 100644
--- a/src/webserver/SslHttpSession.h
+++ b/src/webserver/SslHttpSession.h
@@ -1,5 +1,4 @@
-#ifndef RIPPLE_REPORTING_HTTPS_SESSION_H
-#define RIPPLE_REPORTING_HTTPS_SESSION_H
+#pragma once
 
 #include <webserver/HttpBase.h>
 
@@ -126,5 +125,3 @@ public:
         // At this point the connection is closed gracefully
     }
 };
-
-#endif  // RIPPLE_REPORTING_HTTPS_SESSION_H
diff --git a/src/webserver/SslWsSession.h b/src/webserver/SslWsSession.h
index 111d1780..39532d03 100644
--- a/src/webserver/SslWsSession.h
+++ b/src/webserver/SslWsSession.h
@@ -1,5 +1,4 @@
-#ifndef RIPPLE_REPORTING_SSL_WS_SESSION_H
-#define RIPPLE_REPORTING_SSL_WS_SESSION_H
+#pragma once
 
 #include <boost/asio/dispatch.hpp>
 #include <boost/beast/core.hpp>
@@ -223,5 +222,3 @@ private:
             ->run(std::move(req_));
     }
 };
-
-#endif  // RIPPLE_REPORTING_SSL_WS_SESSION_H
diff --git a/src/webserver/WsBase.h b/src/webserver/WsBase.h
index 250dc0e2..14de053a 100644
--- a/src/webserver/WsBase.h
+++ b/src/webserver/WsBase.h
@@ -1,5 +1,4 @@
-#ifndef RIPPLE_REPORTING_WS_BASE_SESSION_H
-#define RIPPLE_REPORTING_WS_BASE_SESSION_H
+#pragma once
 
 #include <backend/BackendInterface.h>
 #include <etl/ETLSource.h>
@@ -444,5 +443,3 @@ public:
         do_read();
     }
 };
-
-#endif  // RIPPLE_REPORTING_WS_BASE_SESSION_H
diff --git a/unittests/util/Fixtures.h b/unittests/util/Fixtures.h
index 649e22f9..96923f98 100644
--- a/unittests/util/Fixtures.h
+++ b/unittests/util/Fixtures.h
@@ -1,5 +1,4 @@
-#ifndef CLIO_UNITTEST_FIXTURES_H
-#define CLIO_UNITTEST_FIXTURES_H
+#pragma once
 
 #include <ios>
 #include <mutex>
@@ -89,5 +88,3 @@ protected:
         boost::log::core::get()->set_logging_enabled(false);
     }
 };
-
-#endif  // CLIO_UNITTEST_FIXTURES_H