diff --git a/ci/test/00_setup_env_native_fuzz.sh b/ci/test/00_setup_env_native_fuzz.sh
index 18929cc2b2f0..7ee4a50eb967 100755
--- a/ci/test/00_setup_env_native_fuzz.sh
+++ b/ci/test/00_setup_env_native_fuzz.sh
@@ -9,7 +9,7 @@ export LC_ALL=C.UTF-8
 export CONTAINER_NAME=ci_native_fuzz
 export PACKAGES="clang llvm python3 libevent-dev bsdmainutils libboost-dev"
 export DEP_OPTS="NO_UPNP=1 DEBUG=1"
-export CPPFLAGS="-DDEBUG_LOCKORDER -DARENA_DEBUG"
+export CPPFLAGS="-DDEBUG_LOCKORDER -DARENA_DEBUG -DBOOST_MULTI_INDEX_ENABLE_SAFE_MODE"
 export PYZMQ=true
 export RUN_UNIT_TESTS=false
 export RUN_FUNCTIONAL_TESTS=false
diff --git a/ci/test/00_setup_env_native_fuzz_with_valgrind.sh b/ci/test/00_setup_env_native_fuzz_with_valgrind.sh
index 1b5728feb84c..45ad14f545ad 100755
--- a/ci/test/00_setup_env_native_fuzz_with_valgrind.sh
+++ b/ci/test/00_setup_env_native_fuzz_with_valgrind.sh
@@ -15,5 +15,5 @@ export RUN_FUZZ_TESTS=true
 export FUZZ_TESTS_CONFIG="--valgrind"
 export GOAL="install"
 # Temporarily pin dwarf 4, until valgrind can understand clang's dwarf 5
-export BITCOIN_CONFIG="--enable-fuzz --with-sanitizers=fuzzer CC=clang-18 CXX=clang++-18 CFLAGS='-gdwarf-4' CXXFLAGS='-gdwarf-4'"
+export BITCOIN_CONFIG="--enable-fuzz --with-sanitizers=fuzzer CC=clang-18 CXX=clang++-18 CFLAGS='-gdwarf-4' CPPFLAGS='-DBOOST_MULTI_INDEX_ENABLE_SAFE_MODE' CXXFLAGS='-gdwarf-4'"
 export CCACHE_SIZE=200M
diff --git a/ci/test/00_setup_env_native_multiprocess.sh b/ci/test/00_setup_env_native_multiprocess.sh
index 7ab95903d131..855f672550fc 100755
--- a/ci/test/00_setup_env_native_multiprocess.sh
+++ b/ci/test/00_setup_env_native_multiprocess.sh
@@ -13,7 +13,7 @@ export DEP_OPTS="MULTIPROCESS=1 CC=clang-18 CXX=clang++-18"
 export RUN_TIDY=true
 export GOAL="install"
 export TEST_RUNNER_EXTRA="--v2transport"
-export BITCOIN_CONFIG="--with-boost-process --enable-debug CC=clang-18 CXX=clang++-18" # Use clang to avoid OOM
+export BITCOIN_CONFIG="--with-boost-process --enable-debug CC=clang-18 CXX=clang++-18 CPPFLAGS='-DBOOST_MULTI_INDEX_ENABLE_SAFE_MODE'" # Use clang to avoid OOM
 # Additional flags for RUN_TIDY
 export BITCOIN_CONFIG="${BITCOIN_CONFIG} --disable-hardening CFLAGS='-O0 -g0' CXXFLAGS='-O0 -g0 -Wno-error=documentation'"
 export BITCOIND=dash-node  # Used in functional tests
diff --git a/configure.ac b/configure.ac
index ac4bd086422d..cf4407920939 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1482,10 +1482,6 @@ fi
   dnl we don't use multi_index serialization
   BOOST_CPPFLAGS="$BOOST_CPPFLAGS -DBOOST_MULTI_INDEX_DISABLE_SERIALIZATION"
 
-  if test "$enable_debug" = "yes" || test "$enable_fuzz" = "yes"; then
-    BOOST_CPPFLAGS="$BOOST_CPPFLAGS -DBOOST_MULTI_INDEX_ENABLE_SAFE_MODE"
-  fi
-
 dnl Prevent use of std::unary_function, which was removed in C++17,
 dnl and will generate warnings with newer compilers for Boost
 dnl older than 1.80.