diff --git a/util/Makefile.sources b/util/Makefile.sources
index a64099e9f..4459b0c88 100644
--- a/util/Makefile.sources
+++ b/util/Makefile.sources
@@ -47,6 +47,7 @@ HB_SUBSET_CLI_sources = \
 	options.hh \
 	output-options.hh \
 	text-options.hh \
+	helper-subset.hh \
 	$(NULL)
 
 HB_OT_SHAPE_CLOSURE_sources = \
diff --git a/util/helper-subset.hh b/util/helper-subset.hh
index 067a62b71..f0357f2e8 100644
--- a/util/helper-subset.hh
+++ b/util/helper-subset.hh
@@ -27,6 +27,7 @@
 #define HELPER_SUBSET_HH
 
 #include "glib.h"
+#include <errno.h>
 #include <math.h>
 #include <stdbool.h>
 #include "hb-subset.h"