diff --git a/libvips/foreign/Makefile.am b/libvips/foreign/Makefile.am
index b118b9ff..e25e6d6e 100644
--- a/libvips/foreign/Makefile.am
+++ b/libvips/foreign/Makefile.am
@@ -39,6 +39,7 @@ libforeign_la_SOURCES = \
 	pngsave.c \
 	ppmload.c \
 	ppmsave.c \
+	quantise.h \
 	quantise.c \
 	radiance.c \
 	radload.c \
@@ -92,4 +93,3 @@ libforeign_la_SOURCES += openslideload.c
 endif # !OPENSLIDE_MODULE
 
 AM_CPPFLAGS = -I${top_srcdir}/libvips/include @VIPS_CFLAGS@ @VIPS_INCLUDES@
-