diff --git a/configure.ac b/configure.ac
index 0edc19d..f9b7cc8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -4,5 +4,42 @@ AC_CONFIG_SRCDIR([main.c])
 # C compiler
 : ${CFLAGS="-O3 -march=native"}
 AC_PROG_CC
-AC_SUBST(ED25519IMPL,[ref10])
+
+ed25519impl=""
+AC_ARG_ENABLE([ref10],
+	[AS_HELP_STRING([--enable-ref10],
+		[use ref10 ed25519 implementation @<:@default=yes@:>@])],
+	[
+		AS_IF([test "x$ed25519impl" != "x" -a "$ed25519impl" != "ref10"],
+			[AC_ERROR([only one ed25519 implementation can be defined"])])
+		ed25519impl="ref10"
+	],
+	[]
+)
+
+AC_ARG_ENABLE([amd64_51_30k],
+	[AS_HELP_STRING([--enable-amd64_51_30k],
+		[use amd64_51_30k ed25519 implementation @<:@default=no@:>@])],
+	[
+		AS_IF([test "x$ed25519impl" != "x" -a "$ed25519impl" != "amd64_51_30k"],
+			[AC_ERROR([only one ed25519 implementation can be defined"])])
+		ed25519impl="amd64_51_30k"
+	],
+	[]
+)
+
+AC_ARG_ENABLE([amd64_64_24k],
+	[AS_HELP_STRING([--enable-amd64_64_24k],
+		[use amd64_64_24k ed25519 implementation @<:@default=no@:>@])],
+	[
+		AS_IF([test "x$ed25519impl" != "x" -a "$ed25519impl" != "amd64_64_24k"],
+			[AC_ERROR([only one ed25519 implementation can be defined"])])
+		ed25519impl="amd64_64_24k"
+	],
+	[]
+)
+
+AS_IF([test "x$ed25519impl" == "x"],[ed25519impl=ref10])
+
+AC_SUBST(ED25519IMPL,["$ed25519impl"])
 AC_OUTPUT(Makefile)