diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5c18098..6476729 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 * Fix basepoint for Ed448
 
+* Enable 64-bit Curve25519 implementation
+
 ## 0.15
 
 * Fix serialization of DH and ECDH
diff --git a/cbits/curve25519/curve25519-donna-c64.c b/cbits/curve25519/curve25519-donna-c64.c
index 9ebd8a1..adcf57c 100644
--- a/cbits/curve25519/curve25519-donna-c64.c
+++ b/cbits/curve25519/curve25519-donna-c64.c
@@ -427,10 +427,8 @@ crecip(felem out, const felem z) {
   /* 2^255 - 21 */ fmul(out, t0, a);
 }
 
-int curve25519_donna(u8 *, const u8 *, const u8 *);
-
 int
-curve25519_donna(u8 *mypublic, const u8 *secret, const u8 *basepoint) {
+cryptonite_curve25519_donna(u8 *mypublic, const u8 *secret, const u8 *basepoint) {
   limb bp[5], x[5], z[5], zmone[5];
   uint8_t e[32];
   int i;
diff --git a/cryptonite.cabal b/cryptonite.cabal
index 0b03d6c..1cb1c10 100644
--- a/cryptonite.cabal
+++ b/cryptonite.cabal
@@ -199,7 +199,6 @@ Library
                    , cbits/cryptonite_salsa.c
                    , cbits/cryptonite_rc4.c
                    , cbits/cryptonite_cpu.c
-                   , cbits/curve25519/curve25519-donna.c
                    , cbits/ed25519/ed25519.c
                    , cbits/ed448/x448.c
                    , cbits/p256/p256.c
@@ -225,6 +224,11 @@ Library
                    , cbits/cryptonite_scrypt.c
   include-dirs:  cbits cbits/ed25519
 
+  if arch(x86_64)
+    C-sources: cbits/curve25519/curve25519-donna-c64.c
+  else
+    C-sources: cbits/curve25519/curve25519-donna.c
+
   -- FIXME armel or mispel is also little endian.
   -- might be a good idea to also add a runtime autodetect mode.
   -- ARCH_ENDIAN_UNKNOWN