diff --git a/Makefile.am b/Makefile.am
index ed9e766fd409aa84c6ce8477865ce3a317ce71d4..0330059db6b11e4ffbda7b9679ac1d7a64421b7c 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -39,7 +39,7 @@ libnettle_a_SOURCES = aes.c aes.h aes-internal.h \
 		      serpent.c serpent.h serpent_sboxes.h serpent-meta.c \
 		      twofish.c twofish.h twofish-meta.c \
 		      yarrow.h yarrow256.c yarrow_key_event.c \
-		      sexp.h sexp.c sexp_format.c sexp-transport.c \
+		      sexp.h sexp.c sexp-format.c sexp-transport.c \
 		      bignum.h bignum.c bignum-random.c \
 		      rsa.h rsa.c rsa_md5.c rsa_sha1.c \
 		      rsa-encrypt.c rsa-decrypt.c \