https://bugs.gentoo.org/426890
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -5,4 +5,4 @@
 		ranking.c ranking.h your.c your.h
 
-CFLAGS = @X_CFLAGS@ @KXL_CFLAGS@
+AM_CFLAGS = @X_CFLAGS@ @KXL_CFLAGS@
 LIBS = @X_LIBS@ -lX11 @KXL_LIBS@ -lKXL