diff --git a/pika-build-config/v3setup.sh b/pika-build-config/v3setup.sh
index 37c2949a7..4ade59fef 100644
--- a/pika-build-config/v3setup.sh
+++ b/pika-build-config/v3setup.sh
@@ -4,10 +4,10 @@ export PIKA_BUILD_ARCH="amd64-v3"
 export PIKA_PBUILDER_INIT="pika-pbuilder-amd64-v3-init"
 export PIKA_PBUILDER_BUILD="pika-pbuilder-amd64-v3-build"
 export DEBIAN_FRONTEND="noninteractive"
-export DEB_BUILD_MAINT_OPTIONS="optimize=-march=x86-64-v3 -O3 -w -DQT_NO_VERSION_TAGGING -D_FORTIFY_SOURCE=2 -Wno-incompatible-pointer-types -Wno-error"
-export DEB_CFLAGS_MAINT_APPEND="-march=x86-64-v3 -O3 -w -DQT_NO_VERSION_TAGGING -D_FORTIFY_SOURCE=2 -Wno-incompatible-pointer-types -Wno-error"
-export DEB_CPPFLAGS_MAINT_APPEND="-march=x86-64-v3 -O3 -w -DQT_NO_VERSION_TAGGING -D_FORTIFY_SOURCE=2 -Wno-incompatible-pointer-types -Wno-error"
-export DEB_CXXFLAGS_MAINT_APPEND="-march=x86-64-v3 -O3 -w -DQT_NO_VERSION_TAGGING -D_FORTIFY_SOURCE=2 -Wno-incompatible-pointer-types -Wno-error"
+export DEB_BUILD_MAINT_OPTIONS="optimize=-march=x86-64-v3 -O3 -w -DQT_NO_VERSION_TAGGING -Wno-incompatible-pointer-types -Wno-error"
+export DEB_CFLAGS_MAINT_APPEND="-march=x86-64-v3 -O3 -w -DQT_NO_VERSION_TAGGING -Wno-incompatible-pointer-types -Wno-error"
+export DEB_CPPFLAGS_MAINT_APPEND="-march=x86-64-v3 -O3 -w -DQT_NO_VERSION_TAGGING -Wno-incompatible-pointer-types -Wno-error"
+export DEB_CXXFLAGS_MAINT_APPEND="-march=x86-64-v3 -O3 -w -DQT_NO_VERSION_TAGGING -Wno-incompatible-pointer-types -Wno-error"
 export DEB_LDFLAGS_MAINT_APPEND="-march=x86-64-v3 -O3 -w -DQT_NO_VERSION_TAGGING"
 export DEB_BUILD_OPTIONS="nocheck notest terse"
 export DPKG_GENSYMBOLS_CHECK_LEVEL=0