diff --git a/lib/libopus/Makefile.am b/lib/libopus/Makefile.am
index b63f4ac2..ab7028b5 100644
--- a/lib/libopus/Makefile.am
+++ b/lib/libopus/Makefile.am
@@ -143,7 +143,6 @@ libopus_internal_a_CFLAGS = \
 	-DOPUS_BUILD \
 	-DVAR_ARRAYS \
 	-DUSE_ALLOCA \
-	-DHAVE_ALLOCA_H \
 	-g \
 	-I$(srcdir)/include \
 	-I$(srcdir)/celt \