diff --git a/openwrtbuilder b/openwrtbuilder
index 9fe96c5..5562106 100755
--- a/openwrtbuilder
+++ b/openwrtbuilder
@@ -592,7 +592,8 @@ from_source() {
   ((DEBUG)) && make_opts+=("-j1") || make_opts+=("-j$(($(nproc)-1))")
 
   # Make image
-  if ! execute HOST_CFLAGS="-std=c17" ionice -c 3 chrt --idle 0 nice -n19 make "${make_opts[@]}" world; then
+  declare -x HOST_CFLAGS="-std=c17"
+  if ! execute ionice -c 3 chrt --idle 0 nice -n19 make "${make_opts[@]}" world; then
     echo "Error: make failed"
     return 1
   fi