diff --git a/scripts/build/termux_step_setup_toolchain.sh b/scripts/build/termux_step_setup_toolchain.sh
index bfb8f19ae..ce37b5553 100644
--- a/scripts/build/termux_step_setup_toolchain.sh
+++ b/scripts/build/termux_step_setup_toolchain.sh
@@ -2,6 +2,7 @@ termux_step_setup_toolchain() {
 	[ "$TERMUX_PKG_METAPACKAGE" = "true" ] && return
 
 	export CFLAGS=""
+	export CPPFLAGS=""
 	export LDFLAGS="-L${TERMUX_PREFIX}/lib"
 
 	export AS=$TERMUX_HOST_PLATFORM-clang
@@ -69,13 +70,14 @@ termux_step_setup_toolchain() {
 	LDFLAGS+=" -Wl,-z,relro,-z,now"
 
 	if [ "$TERMUX_DEBUG" = "true" ]; then
-		CFLAGS+=" -g3 -O1 -D_FORTIFY_SOURCE=2"
+		CFLAGS+=" -g3 -O1"
+		CPPFLAGS+=" -D_FORTIFY_SOURCE=2 -D__USE_FORTIFY_LEVEL=2"
 	else
 		CFLAGS+=" -Oz"
 	fi
 
 	export CXXFLAGS="$CFLAGS"
-	export CPPFLAGS="-I${TERMUX_PREFIX}/include"
+	export CPPFLAGS+=" -I${TERMUX_PREFIX}/include"
 
 	# If libandroid-support is declared as a dependency, link to it explicitly:
 	if [ "$TERMUX_PKG_DEPENDS" != "${TERMUX_PKG_DEPENDS/libandroid-support/}" ]; then