diff --git a/Makefile.am b/Makefile.am
index 7f88b81b88e69f70d32250094f12d85e71e97689..8ea73088a8c88748b164c7f1c32f3acb876bd356 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -5,7 +5,7 @@ noinst_PROGRAMS = aesdata desdata shadata
 libnettleincludedir = $(includedir)/nettle
 
 lib_LIBRARIES = libnettle.a
-libnettleinclude_HEADERS = aes.h arcfour.h bignum.h blowfish.h \
+libnettleinclude_HEADERS = aes.h arcfour.h arctwo.h bignum.h blowfish.h \
 			   base16.h base64.h buffer.h cast128.h \
 			   cbc.h \
 			   des.h des-compat.h dsa.h \
@@ -28,6 +28,7 @@ libnettle_a_SOURCES = aes.c aes.h aes-internal.h \
 		      aes-encrypt-table.c aes-encrypt.c \
 		      aes-set-encrypt-key.c aes-set-decrypt-key.c aes-meta.c \
 		      arcfour.c arcfour.h arcfour-crypt.c arcfour-meta.c \
+		      arctwo.c arctwo.h arctwo-meta.c \
 		      base16-encode.c base16-decode.c base16-meta.c \
                       base64-encode.c base64-decode.c base64-meta.c base64.h \
 		      cast128.c cast128.h cast128_sboxes.h cast128-meta.c \