diff --git a/src/Makefile.am b/src/Makefile.am
index 8a4e7cdc4b849e8f99bdf9a3dbda9b30fa986332..6ebc3ea6cb81f7445a03728158fa877283d2c9db 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -46,9 +46,9 @@ AM_SOURCES = space.c runner.c queue.c task.c cell.c engine.c \
 # Include files for distribution, not installation.
 nobase_noinst_HEADERS = approx_math.h atomic.h cycle.h error.h inline.h kernel.h vector.h \
 		 runner_doiact.h runner_doiact_grav.h units.h intrinsics.h minmax.h \
-		 gravity.h \
-		 gravity/Default/gravity.h gravity/Default/runner_iact_grav.h \
-		 gravity/Default/gravity_part.h \
+		 gravity.h gravity_io.h \
+		 gravity/Default/gravity.h gravity/Default/runner_iact_grav.h gravity/Default/gravity_io.h \
+		 gravity/Default/gravity_debug.h gravity/Default/gravity_part.h  \
 	 	 hydro.h hydro_io.h \
 		 hydro/Minimal/hydro.h hydro/Minimal/hydro_iact.h hydro/Minimal/hydro_io.h \
                  hydro/Minimal/hydro_debug.h hydro/Minimal/hydro_part.h \