diff --git a/Makefile.am.in b/Makefile.am.in
index 7f56d62fbb614e8e3af8c846a94fe741e7217ef4..1051e5159038e574a23c21735d8dc184b5a8b9f5 100644
--- a/Makefile.am.in
+++ b/Makefile.am.in
@@ -26,7 +26,7 @@ BUILT_SOURCES =	desSmallFips.c desSmallCore.c desQuickFips.c desQuickCore.c \
 
 libsymmetric_a_SOURCES = desCode.h desKerb.c desUtil.c desQuick.c \
       $(BUILT_SOURCES) \
-      sha.c md5.c idea.c arcfour.c cast.c blowfish.c
+      sha.c md5.c idea.c arcfour.c cast.c blowfish.c twofish.c
 
 # Generate DES headers.
 $(des_headers): desdata