diff --git a/test_build.sh b/test_build.sh
index 3ab5319..a63b679 100755
--- a/test_build.sh
+++ b/test_build.sh
@@ -1,4 +1,5 @@
 #!/bin/sh
 set -e
 
-make CONFIG_EVERYTHING=yes WARNERROR=yes
+${MAKECMD:-make} clean
+${MAKECMD:-make} -j${CPUS:-$(nproc)} CC="${CC:-ccache cc}" CONFIG_EVERYTHING=yes