diff --git a/CMakeLists.txt b/CMakeLists.txt
index 821ec5fba..64b180ad6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,12 +3,27 @@
 
 cmake_minimum_required(VERSION 3.12)
 
+# CMake 4.x removed compatibility with cmake_minimum_required(<3.5), which
+# several bundled subprojects (bls, secp256k1, leveldb, univalue, qt) still
+# declare. Allow them to configure under modern CMake.
+if(NOT DEFINED CMAKE_POLICY_VERSION_MINIMUM)
+	set(CMAKE_POLICY_VERSION_MINIMUM 3.5)
+endif()
+
 project(devault
 	VERSION 1.2.1
 #	DESCRIPTION "DeVault is a full node implementation of the DeVault protocol."
 #	HOMEPAGE_URL "https://www.devault.cc"
 )
 
+# Modern libstdc++ (GCC 13+) no longer transitively includes many standard
+# headers (<cstdint>, <stdexcept>, containers, ...) that this 2019-era code
+# relied on. Force-include a small compatibility prelude into every C++ TU
+# instead of editing hundreds of files.
+add_compile_options(
+	"$<$<COMPILE_LANGUAGE:CXX>:-include;${CMAKE_CURRENT_SOURCE_DIR}/src/compat/modern_prelude.h>"
+)
+
 enable_testing()
 
 # Package information
diff --git a/cmake/modules/FindBerkeleyDB.cmake b/cmake/modules/FindBerkeleyDB.cmake
index c71865f5a..d5fc284bd 100644
--- a/cmake/modules/FindBerkeleyDB.cmake
+++ b/cmake/modules/FindBerkeleyDB.cmake
@@ -10,19 +10,21 @@ find_brew_prefix(BREW_HINT berkeley-db)
 
 find_path(BDB_INCLUDE_DIR
 	NAMES db.h
+	PATH_SUFFIXES db5.3 db5 db4.8 db4
 	HINTS ${BREW_HINT}
 )
 find_library(BDB_LIBRARY
-	NAMES db libdb
+	NAMES db libdb db-5.3 db-5 db-4.8
 	HINTS ${BREW_HINT}
 )
 
 find_path(BDBXX_INCLUDE_DIR
 	NAMES db_cxx.h
+	PATH_SUFFIXES db5.3 db5 db4.8 db4
 	HINTS ${BREW_HINT}
 )
 find_library(BDBXX_LIBRARY
-	NAMES db_cxx libdb_cxx
+	NAMES db_cxx libdb_cxx db_cxx-5.3 db_cxx-5 db_cxx-4.8
 	HINTS ${BREW_HINT}
 )
 
diff --git a/cmake/modules/FindMiniupnpc.cmake b/cmake/modules/FindMiniupnpc.cmake
index c2b0b8db3..4ef7138f1 100644
--- a/cmake/modules/FindMiniupnpc.cmake
+++ b/cmake/modules/FindMiniupnpc.cmake
@@ -21,7 +21,10 @@ if(MINIUPNPC_INCLUDE_DIR)
 	set(CMAKE_REQUIRED_INCLUDES ${MINIUPNPC_INCLUDE_DIR})
 	foreach(_miniupnpc_header ${MINIUPNPC_REQUIRED_HEADERS})
 		sanitize_variable(HAVE_MINIUPNPC_ ${_miniupnpc_header} HEADER_FOUND)
-		check_include_files(${_miniupnpc_header} ${HEADER_FOUND})
+		# Prepend stddef.h: newer miniupnpc headers (2.3.x) reference size_t
+		# without including it, which would otherwise fail this self-compile
+		# check and wrongly mark miniupnpc as missing.
+		check_include_files("stddef.h;${_miniupnpc_header}" ${HEADER_FOUND})
 		if(NOT ${HEADER_FOUND})
 			set(MINIUPNPC_MISSING_HEADER ON)
 		endif()
diff --git a/src/compat/modern_prelude.h b/src/compat/modern_prelude.h
new file mode 100644
index 000000000..bccd32dfd
--- /dev/null
+++ b/src/compat/modern_prelude.h
@@ -0,0 +1,36 @@
+// Compatibility prelude force-included for all C++ TUs (see top-level
+// CMAKE_CXX_FLAGS "-include"). Modern libstdc++ (GCC 13+) no longer pulls
+// these in transitively the way the 2019-era code assumed. Including the
+// common set here once avoids sprinkling includes across the tree (and
+// avoids many slow rebuild cycles) just to build on a current toolchain.
+#ifndef DEVAULT_COMPAT_MODERN_PRELUDE_H
+#define DEVAULT_COMPAT_MODERN_PRELUDE_H
+
+// C library shims
+#include <cstdint>
+#include <cstdio>
+#include <cstring>
+#include <cstdlib>
+#include <cstddef>
+#include <climits>
+
+// Common utilities
+#include <stdexcept>
+#include <limits>
+#include <memory>
+#include <utility>
+#include <algorithm>
+#include <functional>
+#include <iterator>
+
+// Common containers
+#include <array>
+#include <vector>
+#include <deque>
+#include <queue>
+#include <list>
+#include <set>
+#include <map>
+#include <string>
+
+#endif // DEVAULT_COMPAT_MODERN_PRELUDE_H
diff --git a/src/net.cpp b/src/net.cpp
index e6e2dea65..18e5599d3 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -1420,7 +1420,13 @@ static void ThreadMapPort() {
     struct IGDdatas data;
     int r;
 
+#if MINIUPNPC_API_VERSION >= 18
+    char wanaddr[64];
+    r = UPNP_GetValidIGD(devlist, &urls, &data, lanaddr, sizeof(lanaddr),
+                         wanaddr, sizeof(wanaddr));
+#else
     r = UPNP_GetValidIGD(devlist, &urls, &data, lanaddr, sizeof(lanaddr));
+#endif
     if (r == 1) {
         if (fDiscover) {
             char externalIPAddress[40];
diff --git a/src/support/lockedpool.cpp b/src/support/lockedpool.cpp
index 1c5271f8a..a19fee9e7 100644
--- a/src/support/lockedpool.cpp
+++ b/src/support/lockedpool.cpp
@@ -25,6 +25,7 @@
 #endif
 
 #include <algorithm>
+#include <stdexcept>
 
 LockedPoolManager *LockedPoolManager::_instance = nullptr;
 std::once_flag LockedPoolManager::init_flag;
diff --git a/src/validation.cpp b/src/validation.cpp
index c2ddbf562..52861a617 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -54,7 +54,9 @@
 #include <dstencode.h> // Temporary
 
 #include <atomic>
+#include <deque>
 #include <future>
+#include <queue>
 #include <sstream>
 #include <thread>