diff --git a/Makefile.am b/Makefile.am
index 162c961..3034569 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -15,7 +15,7 @@
 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 # USA.
 
-AM_CFLAGS = -Wall -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 @libpng_CFLAGS@ @opus_CFLAGS@
+AM_CFLAGS = -Wall -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 @opus_CFLAGS@
 
 SUBDIRS=po