diff --git a/Makefile.am b/Makefile.am
index 7277034abb8c68127efed0c66d3bdb99e78f1fe8..ffa0349ba3c7dca5b1f5b1bc84138c65304ecd96 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -10,7 +10,8 @@ libnettleinclude_HEADERS = aes.h arcfour.h des.h md5.h sha1.h
 libnettle_a_SOURCES = aes.c aes.h arcfour.c arcfour.h blowfish.h blowfish.c \
 		      des.c des.h \
 		      md5.c md5.h sha1.c sha1.h \
-		      serpent.c serpent.h serpent_sboxes.h
+		      serpent.c serpent.h serpent_sboxes.h \
+		      twofish.c twofish.h
 
 libnettle_a_LIBADD = @LIBOBJS@