diff --git a/pika-build-config/ltosetup.sh b/pika-build-config/ltosetup.sh
index e61f9e896..645777d82 100755
--- a/pika-build-config/ltosetup.sh
+++ b/pika-build-config/ltosetup.sh
@@ -4,10 +4,10 @@ export PIKA_BUILD_ARCH="amd64-v3"
 export PIKA_PBUILDER_INIT="pika-pbuilder-amd64-v3-lto-init"
 export PIKA_PBUILDER_BUILD="pika-pbuilder-amd64-v3-lto-build"
 export DEBIAN_FRONTEND="noninteractive"
-export DEB_BUILD_MAINT_OPTIONS="optimize=+lto -march=x86-64-v3 -O3 -flto -fuse-linker-plugin -falign-functions=32 -w -DQT_NO_VERSION_TAGGING -D_FORTIFY_SOURCE=2"
-export DEB_CFLAGS_MAINT_APPEND="-march=x86-64-v3 -O3 -flto -fuse-linker-plugin -falign-functions=32 -w -DQT_NO_VERSION_TAGGING -D_FORTIFY_SOURCE=2"
-export DEB_CPPFLAGS_MAINT_APPEND="-march=x86-64-v3 -O3 -flto -fuse-linker-plugin -falign-functions=32 -w -DQT_NO_VERSION_TAGGING -D_FORTIFY_SOURCE=2"
-export DEB_CXXFLAGS_MAINT_APPEND="-march=x86-64-v3 -O3 -flto -fuse-linker-plugin -falign-functions=32 -w -DQT_NO_VERSION_TAGGING -D_FORTIFY_SOURCE=2"
+export DEB_BUILD_MAINT_OPTIONS="optimize=+lto -march=x86-64-v3 -O3 -flto -fuse-linker-plugin -falign-functions=32 -w -DQT_NO_VERSION_TAGGING"
+export DEB_CFLAGS_MAINT_APPEND="-march=x86-64-v3 -O3 -flto -fuse-linker-plugin -falign-functions=32 -w -DQT_NO_VERSION_TAGGING"
+export DEB_CPPFLAGS_MAINT_APPEND="-march=x86-64-v3 -O3 -flto -fuse-linker-plugin -falign-functions=32 -w -DQT_NO_VERSION_TAGGING"
+export DEB_CXXFLAGS_MAINT_APPEND="-march=x86-64-v3 -O3 -flto -fuse-linker-plugin -falign-functions=32 -w -DQT_NO_VERSION_TAGGING"
 export DEB_LDFLAGS_MAINT_APPEND="-march=x86-64-v3 -O3 -flto -fuse-linker-plugin -falign-functions=32 -w -DQT_NO_VERSION_TAGGING"
 export DEB_BUILD_OPTIONS="nocheck notest terse"
 export DPKG_GENSYMBOLS_CHECK_LEVEL=0