diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2ab9a20b0..71e1adfd2 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -462,6 +462,7 @@ set (wsjt_FSRCS
   lib/jtmsg.f90
   lib/libration.f90
   lib/lorentzian.f90
+  lib/fst4/lorentzian_fading.f90
   lib/lpf1.f90
   lib/mixlpf.f90
   lib/makepings.f90