diff --git a/src/Makefile.am b/src/Makefile.am
index cafa18dd..05fb81ff 100755
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -76,6 +76,7 @@ crater/crater_tally_true.f90\
 crater/crater_tally_observed.f90\
 crater/crater_slope_collapse.f90\
 crater/crater_soften.f90\
+crater/crater_soften_accumulate.f90\
 crater/crater_subpixel_diffusion.f90\
 crater/crater_make_list.f90\
 crater/crater_critical_slope.f90\