diff --git a/simgear/props/Makefile.am b/simgear/props/Makefile.am
index 7196e8a8..81a7228b 100644
--- a/simgear/props/Makefile.am
+++ b/simgear/props/Makefile.am
@@ -6,6 +6,7 @@ include_HEADERS = \
 	condition.hxx \
 	props.hxx \
 	props_io.hxx \
+	propsfwd.hxx \
 	AtomicChangeListener.hxx \
 	ExtendedPropertyAdapter.hxx \
 	propertyObject.hxx \