diff --git a/src/Makefile.am b/src/Makefile.am
index c77b2aa..23625a2 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -45,5 +45,5 @@
 BUILT_SOURCES = css.h
 CLEANFILES = css.h
 css.h: csstoh powertop.css
-	./csstoh powertop.css css.h
+	./csstoh "$(srcdir)"/powertop.css css.h