diff --git a/Makefile.in b/Makefile.in
index c072aa6..7c8c6e0 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -19,6 +19,7 @@ ED25519OBJ= $(ED25519_@ED25519IMPL@)
 
 MAINOBJ= \
 	main.c.o \
+	cpucount.c.o \
 	base32_to.c.o \
 	base32_from.c.o \
 	$(ED25519OBJ) \
@@ -91,6 +92,7 @@ base16_from.c.o: types.h base16.h
 base16_to.c.o: types.h base16.h
 base32_from.c.o: types.h base32.h
 base32_to.c.o: types.h base32.h
+cpucount.c.o: cpucount.h
 ed25519/amd64-51-30k/batch.c.o: ed25519/amd64-51-30k/crypto_sign.h
 ed25519/amd64-51-30k/batch.c.o: ed25519/amd64-51-30k/ed25519.h
 ed25519/amd64-51-30k/batch.c.o: ed25519/amd64-51-30k/crypto_verify_32.h
@@ -351,12 +353,12 @@ ed25519/ref10/sign.c.o: ed25519/amd64-51-30k/crypto_hash_sha512.h
 ed25519/ref10/sign.c.o: ed25519/ref10/ge.h ed25519/ref10/fe.h
 ed25519/ref10/sign.c.o: ed25519/ref10/crypto_int32.h ed25519/ref10/sc.h
 keccak.c.o: types.h keccak.h
-main.c.o: types.h likely.h vec.h base32.h keccak.h ed25519/ed25519.h
-main.c.o: ed25519/ref10/ed25519.h ed25519/ref10/ge.h ed25519/ref10/fe.h
-main.c.o: ed25519/ref10/crypto_int32.h ed25519/amd64-51-30k/ed25519.h
-main.c.o: ed25519/amd64-51-30k/ge25519.h ed25519/amd64-51-30k/fe25519.h
-main.c.o: ed25519/amd64-51-30k/sc25519.h ed25519/amd64-64-24k/ed25519.h
-main.c.o: ed25519/amd64-64-24k/ge25519.h
+main.c.o: types.h likely.h vec.h base32.h cpucount.h keccak.h
+main.c.o: ed25519/ed25519.h ed25519/ref10/ed25519.h ed25519/ref10/ge.h
+main.c.o: ed25519/ref10/fe.h ed25519/ref10/crypto_int32.h
+main.c.o: ed25519/amd64-51-30k/ed25519.h ed25519/amd64-51-30k/ge25519.h
+main.c.o: ed25519/amd64-51-30k/fe25519.h ed25519/amd64-51-30k/sc25519.h
+main.c.o: ed25519/amd64-64-24k/ed25519.h ed25519/amd64-64-24k/ge25519.h
 main.c.o: ed25519/ed25519-donna/ed25519-donna.h
 main.c.o: ed25519/ed25519-donna/ed25519-donna-portable.h
 main.c.o: ed25519/ed25519-donna/ed25519-donna-portable-identify.h
diff --git a/ed25519/ed25519-donna b/ed25519/ed25519-donna
deleted file mode 160000
index 8757bd4..0000000
--- a/ed25519/ed25519-donna
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit 8757bd4cd209cb032853ece0ce413f122eef212c
diff --git a/main.c b/main.c
index b1bedec..af3d327 100644
--- a/main.c
+++ b/main.c
@@ -13,6 +13,7 @@
 #include "likely.h"
 #include "vec.h"
 #include "base32.h"
+#include "cpucount.h"
 #include "keccak.h"
 #include "ed25519/ed25519.h"
 
@@ -169,7 +170,7 @@ static void loadfilterfile(const char *fname)
 	FILE *f = fopen(fname,"r");
 	while (fgets(buf,sizeof(buf),f)) {
 		for (char *p = buf;*p;++p) {
-			if(*p == '\n') {
+			if (*p == '\n') {
 				*p = 0;
 				break;
 			}
@@ -707,8 +708,9 @@ int main(int argc,char **argv)
 	}
 
 	if (numthreads <= 0) {
-		// TODO: autodetect
-		numthreads = 1;
+		numthreads = cpucount();
+		if (numthreads <= 0)
+			numthreads = 1;
 	}
 
 	signal(SIGTERM,termhandler);