diff --git a/opus_headers.mk b/opus_headers.mk
index c8f63eab..27596f2a 100644
--- a/opus_headers.mk
+++ b/opus_headers.mk
@@ -1,6 +1,7 @@
 OPUS_HEAD = \
 include/opus.h \
 include/opus_multistream.h \
+include/opus_projection.h \
 src/opus_private.h \
 src/analysis.h \
 src/mapping_matrix.h \