diff --git a/.gitignore b/.gitignore
index e6c91ec28..7eaf3d071 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,7 +1,34 @@
-obj/*
 bench
+bench.exe
 tests
+tests.exe
 *.so
 *.a
-config.mk
 !.gitignore
+
+Makefile
+configure
+.libs/
+Makefile.in
+aclocal.m4
+autogen.sh
+autom4te.cache/
+config.log
+config.status
+*.tar.gz
+*.la
+libtool
+.deps/
+.dirstamp
+src/build-aux/
+*.lo
+*.o
+*~
+src/libsecp256k1-config.h
+src/libsecp256k1-config.h.in
+m4/libtool.m4
+m4/ltoptions.m4
+m4/ltsugar.m4
+m4/ltversion.m4
+m4/lt~obsolete.m4
+src/stamp-h1
diff --git a/Makefile b/Makefile
deleted file mode 100644
index ea88584cf..000000000
--- a/Makefile
+++ /dev/null
@@ -1,49 +0,0 @@
-$(shell CC=$(CC) YASM=$(YASM) ./configure)
-include config.mk
-
-FILES := src/*.h src/impl/*.h
-
-JAVA_FILES := src/java/org_bitcoin_NativeSecp256k1.h src/java/org_bitcoin_NativeSecp256k1.c
-
-OBJS :=
-
-ifeq ($(USE_ASM), 1)
-    OBJS := $(OBJS) obj/field_5x52_asm.o
-endif
-STD="gnu99"
-
-default: tests libsecp256k1.a libsecp256k1.so
-
-clean:
-	rm -rf obj/*.o bench tests *.a *.so config.mk
-
-obj/field_5x52_asm.o: src/field_5x52_asm.asm
-	$(YASM) -f elf64 -o obj/field_5x52_asm.o src/field_5x52_asm.asm
-
-obj/secp256k1.o: $(FILES) src/secp256k1.c include/secp256k1.h
-	$(CC) -fPIC -std=$(STD) $(CFLAGS) $(CFLAGS_EXTRA) -DNDEBUG -$(OPTLEVEL) src/secp256k1.c -c -o obj/secp256k1.o
-
-bench: $(FILES) src/bench.c $(OBJS)
-	$(CC) -fPIC -std=$(STD) $(CFLAGS) $(CFLAGS_EXTRA) $(CFLAGS_TEST_EXTRA) -DNDEBUG -$(OPTLEVEL) src/bench.c $(OBJS) $(LDFLAGS_EXTRA) $(LDFLAGS_TEST_EXTRA) -o bench
-
-tests: $(FILES) src/tests.c $(OBJS)
-	$(CC) -std=$(STD) $(CFLAGS) $(CFLAGS_EXTRA) $(CFLAGS_TEST_EXTRA) -DVERIFY -fstack-protector-all -$(OPTLEVEL) -ggdb3 src/tests.c $(OBJS) $(LDFLAGS_EXTRA) $(LDFLAGS_TEST_EXTRA) -o tests
-
-coverage: $(FILES) src/tests.c $(OBJS)
-	rm -rf tests.gcno tests.gcda tests_cov
-	$(CC) -std=$(STD) $(CFLAGS) $(CFLAGS_EXTRA) $(CFLAGS_TEST_EXTRA) -DVERIFY --coverage -$(OPTLEVEL) -g src/tests.c $(OBJS) $(LDFLAGS_EXTRA) $(LDFLAGS_TEST_EXTRA) -o tests_cov
-	rm -rf lcov
-	mkdir -p lcov
-	cd lcov; lcov --directory ../ --zerocounters
-	cd lcov; ../tests_cov
-	cd lcov; lcov --directory ../ --capture --output-file secp256k1.info
-	cd lcov; genhtml -o . secp256k1.info
-
-libsecp256k1.a: obj/secp256k1.o $(OBJS)
-	$(AR) -rs $@ $(OBJS) obj/secp256k1.o
-
-libsecp256k1.so: obj/secp256k1.o $(OBJS)
-	$(CC) -std=$(STD) $(LDFLAGS_EXTRA) $(OBJS) obj/secp256k1.o -shared -o libsecp256k1.so
-
-libjavasecp256k1.so: $(OBJS) obj/secp256k1.o $(JAVA_FILES)
-	$(CC) -fPIC -std=$(STD) $(CFLAGS) $(CFLAGS_EXTRA) -DNDEBUG -$(OPTLEVEL) -I. src/java/org_bitcoin_NativeSecp256k1.c $(LDFLAGS_EXTRA) $(OBJS) obj/secp256k1.o -shared -o libjavasecp256k1.so
diff --git a/Makefile.am b/Makefile.am
new file mode 100644
index 000000000..a0bf0b229
--- /dev/null
+++ b/Makefile.am
@@ -0,0 +1,63 @@
+ACLOCAL_AMFLAGS = -I m4
+INCLUDES = $(SECP_INCLUDES)
+lib_LTLIBRARIES = libsecp256k1.la
+libsecp256k1_la_SOURCES = src/secp256k1.c
+libsecp256k1_la_CPPFLAGS = -I$(top_srcdir)/include $(SECP_INCLUDES)
+libsecp256k1_la_LIBADD = $(SECP_LIBS)
+include_HEADERS = include/secp256k1.h
+noinst_HEADERS =
+noinst_HEADERS += src/group.h
+noinst_HEADERS += src/num_openssl.h
+noinst_HEADERS += src/num_gmp.h
+noinst_HEADERS += src/ecdsa.h
+noinst_HEADERS += src/ecmult.h
+noinst_HEADERS += src/num.h
+noinst_HEADERS += src/field_10x26.h
+noinst_HEADERS += src/field_5x52.h
+noinst_HEADERS += src/java/org_bitcoin_NativeSecp256k1.h
+noinst_HEADERS += src/util.h
+noinst_HEADERS += src/field_gmp.h
+noinst_HEADERS += src/impl/group.h
+noinst_HEADERS += src/impl/num_openssl.h
+noinst_HEADERS += src/impl/num_gmp.h
+noinst_HEADERS += src/impl/ecdsa.h
+noinst_HEADERS += src/impl/field_5x52_int128.h
+noinst_HEADERS += src/impl/ecmult.h
+noinst_HEADERS += src/impl/num.h
+noinst_HEADERS += src/impl/field_10x26.h
+noinst_HEADERS += src/impl/field_5x52.h
+noinst_HEADERS += src/impl/util.h
+noinst_HEADERS += src/impl/field_gmp.h
+noinst_HEADERS += src/impl/field_5x52_asm.h
+noinst_HEADERS += src/impl/field.h
+noinst_HEADERS += src/field.h
+
+if USE_ASM
+libsecp256k1_la_SOURCES += src/field_5x52_asm.asm
+endif
+
+noinst_PROGRAMS =
+if USE_BENCHMARK
+noinst_PROGRAMS += bench
+bench_SOURCES = src/bench.c
+bench_CPPFLAGS = -DNDEBUG
+bench_LDADD = libsecp256k1.la $(SECP_LIBS)
+bench_LDFLAGS = -static
+endif
+
+if USE_TESTS
+noinst_PROGRAMS += tests
+tests_SOURCES = src/tests.c
+tests_CPPFLAGS = -DVERIFY $(SECP_TEST_INCLUDES)
+tests_LDADD = libsecp256k1.la $(SECP_LIBS) $(SECP_TEST_LIBS)
+tests_LDFLAGS = -static
+TESTS = tests
+endif
+
+EXTRA_DIST = nasm_lt.sh
+
+#x86_64 only
+if USE_ASM
+.asm.lo:
+	$(LIBTOOL) --mode=compile --tag YASM $(srcdir)/nasm_lt.sh $(YASM) -f elf64 $(YAFLAGS) -I$(srcdir) -I. $< -o $@
+endif
diff --git a/configure b/configure
deleted file mode 100755
index c3b95c227..000000000
--- a/configure
+++ /dev/null
@@ -1,173 +0,0 @@
-#!/bin/sh
-
-if test -f config.mk; then
-    exit 0
-fi
-
-if test -z "$CC"; then
-    CC=cc
-fi
-
-if test -z "$YASM"; then
-    YASM=yasm
-fi
-
-# test yasm
-$YASM -f elf64 -o /tmp/secp256k1-$$.o - <<EOF
-	BITS 64
-	GLOBAL testyasm
-	ALIGN 32
-testyasm:
-	xor r9,r9
-EOF
-if [ "$?" = 0 ]; then
-    $CC $CFLAGS -std=c99 -x c -c - -o /tmp/secp256k1-$$-2.o 2>/dev/null <<EOF
-void __attribute__ ((sysv_abi)) testyasm(void);
-int main() {
-    testyasm();
-    return 0;
-}
-EOF
-    $CC $CFLAGS -std=c99 /tmp/secp256k1-$$-2.o /tmp/secp256k1-$$.o -o /dev/null 2>/dev/null
-    if [ "$?" = 0 ]; then
-        HAVE_YASM=1
-    fi
-    rm -rf /tmp/secp256k1-$$-2.o /tmp/secp256k1-$$.o
-fi
-
-# test openssl
-HAVE_OPENSSL=0
-$CC $CFLAGS -std=c99 -x c - -o /dev/null -lcrypto 2>/dev/null <<EOF
-#include <openssl/bn.h>
-int main() {
-    BN_CTX *ctx = BN_CTX_new();
-    BN_CTX_free(ctx);
-    return 0;
-}
-EOF
-if [ "$?" = 0 ]; then
-    HAVE_OPENSSL=1
-fi
-
-# test openssl/EC
-HAVE_OPENSSL_EC=0
-if [ "$HAVE_OPENSSL" = "1" ]; then
-$CC $CFLAGS -std=c99 -x c - -o /dev/null -lcrypto 2>/dev/null <<EOF
-#include <openssl/ec.h>
-#include <openssl/ecdsa.h>
-#include <openssl/obj_mac.h>
-int main() {
-    EC_KEY *eckey = EC_KEY_new_by_curve_name(NID_secp256k1);
-    ECDSA_sign(0, NULL, 0, NULL, NULL, eckey);
-    ECDSA_verify(0, NULL, 0, NULL, 0, eckey);
-    EC_KEY_free(eckey);
-    return 0;
-}
-EOF
-if [ "$?" = 0 ]; then
-    HAVE_OPENSSL_EC=1
-fi
-fi
-
-# test gmp
-HAVE_GMP=0
-$CC $CFLAGS -std=c99 -x c - -o /dev/null -lgmp 2>/dev/null <<EOF
-#include <gmp.h>
-int main() {
-    mpz_t n;
-    mpz_init(n);
-    mpz_clear(n);
-    return 0;
-}
-EOF
-if [ "$?" = 0 ]; then
-    HAVE_GMP=1
-fi
-
-# test __int128
-HAVE_INT128=0
-$CC $CFLAGS -std=c99 -x c - -o /dev/null 2>/dev/null <<EOF
-#include <stdint.h>
-int main() {
-    __int128 x = 0;
-    return 0;
-}
-EOF
-if [ "$?" = 0 ]; then
-    HAVE_INT128=1
-fi
-
-for arg in "$@"; do
-    case "$arg" in
-        --no-yasm)
-            HAVE_YASM=0
-            ;;
-        --no-gmp)
-            HAVE_GMP=0
-            ;;
-        --no-openssl)
-            HAVE_OPENSSL=0
-            ;;
-        --use-endomorphism)
-            USE_ENDOMORPHISM=1
-            ;;
-    esac
-done
-
-LINK_OPENSSL=0
-LINK_GMP=0
-USE_ASM=0
-
-# select field implementation
-if [ "$HAVE_YASM" = "1" ]; then
-    CFLAGS_FIELD="-DUSE_FIELD_5X52 -DUSE_FIELD_5X52_ASM"
-    USE_ASM=1
-elif [ "$HAVE_INT128" = "1" ]; then
-    CFLAGS_FIELD="-DUSE_FIELD_5X52 -DUSE_FIELD_5X52_INT128"
-elif [ "$HAVE_GMP" = "1" ]; then
-    CFLAGS_FIELD="-DUSE_FIELD_GMP"
-    LINK_GMP=1
-else
-    CFLAGS_FIELD="-DUSE_FIELD_10X26"
-fi
-
-# select num implementation
-if [ "$HAVE_GMP" = "1" ]; then
-    CFLAGS_NUM="-DUSE_NUM_GMP -DUSE_FIELD_INV_NUM"
-    LINK_GMP=1
-elif [ "$HAVE_OPENSSL" =  "1" ]; then
-    CFLAGS_NUM="-DUSE_NUM_OPENSSL -DUSE_FIELD_INV_BUILTIN"
-    LINK_OPENSSL=1
-else
-    echo "No usable num implementation found" >&2
-    exit 1
-fi
-
-CFLAGS_EXTRA="$CFLAGS_FIELD $CFLAGS_NUM"
-LDFLAGS_EXTRA=""
-if [ "$LINK_GMP" = "1" ]; then
-    LDFLAGS_EXTRA="-lgmp"
-fi
-if [ "$LINK_OPENSSL" = "1" ]; then
-    LDFLAGS_EXTRA="-lcrypto"
-else
-    if [ "$HAVE_OPENSSL_EC" = "1" ]; then
-        LDFLAGS_TEST_EXTRA="-lcrypto"
-    fi
-fi
-
-CFLAGS_TEST_EXTRA=""
-if [ "$HAVE_OPENSSL_EC" = "1" ]; then
-    CFLAGS_TEST_EXTRA="-DENABLE_OPENSSL_TESTS"
-fi
-if [ "$USE_ENDOMORPHISM" = "1" ]; then
-    CFLAGS_EXTRA="$(CFLAGS_EXTRA) -DUSE_ENDOMORPHISM"
-fi
-echo "CC=$CC" > config.mk
-echo "YASM=$YASM" >>config.mk
-echo "CFLAGS_EXTRA=$CFLAGS_EXTRA" >> config.mk
-echo "CFLAGS_TEST_EXTRA=$CFLAGS_TEST_EXTRA" >> config.mk
-echo "LDFLAGS_EXTRA=$LDFLAGS_EXTRA" >> config.mk
-echo "LDFLAGS_TEST_EXTRA=$LDFLAGS_TEST_EXTRA" >> config.mk
-echo "USE_ASM=$USE_ASM" >>config.mk
-echo "OPTLEVEL=O2" >>config.mk
diff --git a/configure.ac b/configure.ac
new file mode 100644
index 000000000..99de689ca
--- /dev/null
+++ b/configure.ac
@@ -0,0 +1,279 @@
+AC_PREREQ([2.60])
+AC_INIT([libsecp256k1],[0.1])
+AC_CONFIG_AUX_DIR([src/build-aux])
+AC_CONFIG_MACRO_DIR([m4])
+AC_CANONICAL_HOST
+AH_TOP([#ifndef LIBSECP256K1_CONFIG_H])
+AH_TOP([#define LIBSECP256K1_CONFIG_H])
+AH_BOTTOM([#endif //LIBSECP256K1_CONFIG_H])
+AM_INIT_AUTOMAKE([foreign])
+LT_INIT
+
+AC_PROG_CC
+AC_PROG_CPP
+AC_PROG_INSTALL
+AC_PROG_SED
+PKG_PROG_PKG_CONFIG
+
+AC_PROG_CC_C99
+if test x"$ac_cv_prog_cc_c99" == x"no"; then
+  AC_MSG_ERROR([c99 compiler support required])
+fi
+
+case $host in
+  *mingw*)
+     use_pkgconfig=no
+     ;;
+   *)
+     use_pkgconfig=yes
+     ;;
+esac
+
+AC_ARG_ENABLE(benchmark,
+    AS_HELP_STRING([--enable-benchmark],[compile benchmark (default is yes)]),
+    [use_benchmark=$enableval],
+    [use_benchmark=yes])
+
+AC_ARG_ENABLE(tests,
+    AS_HELP_STRING([--enable-tests],[compile tests (default is yes)]),
+    [use_tests=$enableval],
+    [use_tests=yes])
+
+AC_ARG_ENABLE(endomorphism,
+    AS_HELP_STRING([--enable-endomorphism],[enable endomorphism (default is yes)]),
+    [use_endomorphism=$enableval],
+    [use_endomorphism=yes])
+
+AC_ARG_WITH([fields], [AS_HELP_STRING([--with-fields=gmp|int128|x86_64_asm|fallback|auto],
+[Specify Fields Implementation. Default is auto])],[req_field=$withval], [req_field=auto])
+
+AC_ARG_WITH([bignum], [AS_HELP_STRING([--with-bignum=gmp|openssl|auto],
+[Specify Bignum Implementation. Default is auto])],[req_bignum=$withval], [req_bignum=auto])
+
+AC_CHECK_TYPES([__int128])
+
+AC_DEFUN([SECP_INT128_CHECK],[
+has_int128=$ac_cv_type___int128
+if test x"$has_int128" != x"yes" && test x"$set_field" = x"int128"; then
+  AC_MSG_ERROR([$set_field field support explicitly requested but is not compatible with this host])
+fi
+])
+
+AC_DEFUN([SECP_X86_64_ASM_CHECK],[
+if test x"$host_cpu" == x"x86_64"; then
+  AC_CHECK_PROG(YASM, yasm, yasm)
+else
+  if test x"$set_field" = x"x86_64_asm"; then
+    AC_MSG_ERROR([$set_field field support explicitly requested but is not compatible with this host])
+  fi
+fi
+if test x$YASM = x; then
+  if test x"$set_field" = x"x86_64_asm"; then
+    AC_MSG_ERROR([$set_field field support explicitly requested but yasm was not found])
+  fi
+  has_x86_64_asm=no
+else
+  has_x86_64_asm=yes
+fi
+])
+
+AC_DEFUN([SECP_OPENSSL_CHECK],[
+if test x"$use_pkgconfig" = x"yes"; then
+    : #NOP
+  m4_ifdef([PKG_CHECK_MODULES],[
+    PKG_CHECK_MODULES([SSL], [libssl], [has_libssl=yes; AC_DEFINE(HAVE_LIBSSL,1,[Define this symbol if libssl is installed])],[has_libssl=no])
+    PKG_CHECK_MODULES([CRYPTO], [libcrypto], [has_libcrypto=yes; AC_DEFINE(HAVE_LIBCRYPTO,1,[Define this symbol if libcrypto is installed])],[has_libcrypto=no])
+    : #NOP
+  ])
+else
+  AC_CHECK_HEADER(openssl/ssl.h,[AC_CHECK_LIB(ssl, main,[has_libssl=yes; SSL_LIBS=-lssl; AC_DEFINE(HAVE_LIBSSL,1,[Define this symbol if libssl is installed])])])
+  AC_CHECK_HEADER(openssl/crypto.h,[AC_CHECK_LIB(crypto, main,[has_libcrypto=yes; CRYPTO_LIBS=-lcrypto; AC_DEFINE(HAVE_LIBCRYPTO,1,[Define this symbol if libcrypto is installed])]
+)])
+  LIBS=
+fi
+if test x"$has_libssl" == x"yes" && test x"$has_openssl_ec" = x; then
+  AC_MSG_CHECKING(for EC functions in libssl)
+  AC_TRY_COMPILE([
+    #include <openssl/ec.h>
+    #include <openssl/ecdsa.h>
+    #include <openssl/obj_mac.h>],[
+    EC_KEY *eckey = EC_KEY_new_by_curve_name(714);
+    ECDSA_sign(0, NULL, 0, NULL, NULL, eckey);
+    ECDSA_verify(0, NULL, 0, NULL, 0, eckey);
+    EC_KEY_free(eckey);
+  ],[has_openssl_ec=yes], [has_openssl_ec=no])
+  AC_MSG_RESULT([$has_openssl_ec])
+fi
+if test x"$set_bignum" = x"openssl"; then
+  if test x"$has_libssl" != x"yes"; then
+    AC_MSG_ERROR([$set_bignum field support explicitly requested but libssl was not found])
+  fi
+  if test x"$has_libcrypto" != x"yes"; then
+    AC_MSG_ERROR([$set_bignum field support explicitly requested but libcrypto was not found])
+  fi
+fi
+])
+
+AC_DEFUN([SECP_GMP_CHECK],[
+if test x"$has_gmp" != x"yes"; then
+  AC_CHECK_HEADER(gmp.h,[AC_CHECK_LIB(gmp, __gmpz_init,[has_gmp=yes; GMP_LIBS=-lgmp; AC_DEFINE(HAVE_LIBGMP,1,[Define this symbol if libgmp is installed])])])
+fi
+if test x"$set_field" = x"gmp" && test x"$has_gmp" != x"yes"; then
+    AC_MSG_ERROR([$set_field field support explicitly requested but libgmp was not found])
+fi
+if test x"$set_bignum" = x"gmp" && test x"$has_gmp" != x"yes"; then
+    AC_MSG_ERROR([$set_bignum field support explicitly requested but libgmp was not found])
+fi
+])
+
+if test x"$req_field" = x"auto"; then
+  SECP_X86_64_ASM_CHECK
+  if test x"$has_x86_64_asm" = x"yes"; then
+    set_field=x86_64_asm
+  fi
+
+  if test x"$set_field" = x; then
+    SECP_INT128_CHECK
+    if test x"$has_int128" = x"yes"; then
+      set_field=int128
+    fi
+  fi
+
+  if test x"$set_field" = x; then
+    SECP_GMP_CHECK
+    if test x"$has_gmp" = x"yes"; then
+      set_field=gmp
+    fi
+  fi
+
+  if test x"$set_field" = x; then
+    set_field=fallback
+  fi
+else
+  set_field=$req_field
+  case $set_field in
+  x86_64_asm)
+    SECP_X86_64_ASM_CHECK
+    ;;
+  int128)
+    SECP_INT128_CHECK
+    ;;
+  gmp)
+    SECP_GMP_CHECK
+    ;;
+  fallback)
+    ;;
+  *)
+    AC_MSG_ERROR([invalid field implementation selection])
+    ;;
+  esac
+fi
+
+if test x"$req_bignum" = x"auto"; then
+  SECP_GMP_CHECK
+  if test x"$has_gmp" = x"yes"; then
+    set_bignum=gmp
+  fi
+
+  if test x"$set_bignum" = x; then
+    SECP_OPENSSL_CHECK
+    if test x"$has_libssl" = x"yes"; then
+      set_bignum=openssl
+    fi
+  fi
+
+  if test x"$set_bignum" = x; then
+    AC_MSG_ERROR([no working bignum implementation found])
+  fi
+else
+  set_bignum=$req_bignum
+  case $set_bignum in
+  gmp)
+    SECP_GMP_CHECK
+    ;;
+  openssl)
+    SECP_OPENSSL_CHECK
+    ;;
+  *)
+    AC_MSG_ERROR([invalid bignum implementation selection])
+    ;;
+  esac
+fi
+
+# select field implementation
+case $set_field in
+x86_64_asm)
+  AC_DEFINE(USE_FIELD_5X52_ASM, 1, [Define this symbol to use the FIELD_5X52_ASM implementation])
+  AC_DEFINE(USE_FIELD_5X52, 1, [Define this symbol to use the FIELD_5X52 implementation])
+  ;;
+int128)
+  AC_DEFINE(USE_FIELD_5X52_INT128, 1, [Define this symbol to use the FIELD_5X52_INT128 implementation])
+  AC_DEFINE(USE_FIELD_5X52, 1, [Define this symbol to use the FIELD_5X52 implementation])
+  ;;
+gmp)
+  AC_DEFINE(HAVE_LIBGMP,1,[Define this symbol if libgmp is installed])
+  AC_DEFINE(USE_FIELD_GMP, 1, [Define this symbol to use the FIELD_GMP implementation])
+  ;;
+fallback)
+  AC_DEFINE(USE_FIELD_10X26, 1, [Define this symbol to use the FIELD_10X26 implementation])
+  ;;
+*)
+  AC_MSG_ERROR([invalid field implementation])
+  ;;
+esac
+
+# select bignum implementation
+case $set_bignum in
+gmp)
+  AC_DEFINE(HAVE_LIBGMP,1,[Define this symbol if libgmp is installed])
+  AC_DEFINE(USE_NUM_GMP, 1, [Define this symbol to use the gmp implementation])
+  AC_DEFINE(USE_FIELD_INV_NUM, 1, [Define this symbol to use the USE_FIELD_INV_NUM implementation])
+  ;;
+openssl)
+  AC_DEFINE(USE_NUM_OPENSSL, 1,[Define this symbol to use the openssl implementation])
+  AC_DEFINE(USE_FIELD_INV_BUILTIN, 1, [Define this symbol to use the FIELD_INV_BUILTIN implementation])
+  SECP_INCLUDES="$SSL_CFLAGS $CRYPTO_CFLAGS"
+  SECP_LIBS="$CRYPTO_LIBS"
+  ;;
+*)
+  AC_MSG_ERROR([invalid bignum implementation])
+  ;;
+esac
+
+if test x"$use_tests" = x"yes"; then
+  SECP_OPENSSL_CHECK
+  if test x"$has_openssl_ec" == x"yes"; then
+    AC_DEFINE(ENABLE_OPENSSL_TESTS, 1, [Define this symbol if OpenSSL EC functions are available])
+    SECP_TEST_INCLUDES="$SSL_CFLAGS $CRYPTO_CFLAGS"
+    SECP_TEST_LIBS="$CRYPTO_LIBS"
+
+    case $host in
+    *mingw*)
+      SECP_TEST_LIBS="$SECP_TEST_LIBS -lgdi32"
+      ;;
+    esac
+
+  fi
+fi
+
+if test x"$set_field" = x"gmp" || test x"$set_bignum" = x"gmp"; then
+  SECP_LIBS="$SECP_LIBS $GMP_LIBS"
+fi
+
+if test x"$use_endomorphism" = x"yes"; then
+  AC_DEFINE(USE_ENDOMORPHISM, 1, [Define this symbol to use endomorphism])
+fi
+
+AC_MSG_NOTICE([Using field implementation: $set_field])
+AC_MSG_NOTICE([Using bignum implementation: $set_bignum])
+
+AC_CONFIG_HEADERS([src/libsecp256k1-config.h])
+AC_CONFIG_FILES([Makefile])
+AC_SUBST(SECP_INCLUDES)
+AC_SUBST(SECP_LIBS)
+AC_SUBST(SECP_TEST_LIBS)
+AC_SUBST(SECP_TEST_INCLUDES)
+AM_CONDITIONAL([USE_ASM], [test x"$set_field" == x"x86_64_asm"])
+AM_CONDITIONAL([USE_TESTS], [test x"$use_tests" != x"no"])
+AM_CONDITIONAL([USE_BENCHMARK], [test x"$use_benchmark" != x"no"])
+AC_OUTPUT
diff --git a/m4/.empty b/m4/.empty
new file mode 100644
index 000000000..e69de29bb
diff --git a/nasm_lt.sh b/nasm_lt.sh
new file mode 100755
index 000000000..6cd73294c
--- /dev/null
+++ b/nasm_lt.sh
@@ -0,0 +1,57 @@
+#! /bin/sh
+command=""
+infile=""
+o_opt=no
+pic=no
+while [ $# -gt 0 ]; do
+    case "$1" in
+        -DPIC|-fPIC|-fpic|-Kpic|-KPIC)
+            if [ "$pic" != "yes" ] ; then
+                command="$command -DPIC"
+                pic=yes
+            fi
+            ;;
+        -f|-fbin|-faout|-faoutb|-fcoff|-felf|-felf64|-fas86| \
+        -fobj|-fwin32|-fwin64|-frdf|-fieee|-fmacho|-fmacho64)
+            # it's a file format specifier for nasm.
+            command="$command $1"
+            ;;
+        -f*)
+            # maybe a code-generation flag for gcc.
+            ;;
+        -[Ii]*)
+            incdir=`echo "$1" | sed 's/^-[Ii]//'`
+            if [ "x$incdir" = x -a "x$2" != x ] ; then
+                case "$2" in
+                    -*) ;;
+                    *) incdir="$2"; shift;;
+                esac
+            fi
+            if [ "x$incdir" != x ] ; then
+                # In the case of NASM, the trailing slash is necessary.
+                incdir=`echo "$incdir" | sed 's%/*$%/%'`
+                command="$command -I$incdir"
+            fi
+            ;;
+        -o*)
+            o_opt=yes
+            command="$command $1"
+            ;;
+        *.asm)
+            infile=$1
+            command="$command $1"
+            ;;
+        *)
+            command="$command $1"
+            ;;
+    esac
+    shift
+done
+if [ "$o_opt" != yes ] ; then
+    # By default, NASM creates an output file
+    # in the same directory as the input file.
+    outfile="-o `echo $infile | sed -e 's%^.*/%%' -e 's%\.[^.]*$%%'`.o"
+    command="$command $outfile"
+fi
+echo $command
+exec $command
diff --git a/src/field.h b/src/field.h
index 7d187d02c..f31bbe14b 100644
--- a/src/field.h
+++ b/src/field.h
@@ -16,6 +16,10 @@
  *    normality.
  */
 
+#if defined HAVE_CONFIG_H
+#include "libsecp256k1-config.h"
+#endif
+
 #if defined(USE_FIELD_GMP)
 #include "field_gmp.h"
 #elif defined(USE_FIELD_10X26)
diff --git a/src/impl/field.h b/src/impl/field.h
index c43188adc..e4ce62ee8 100644
--- a/src/impl/field.h
+++ b/src/impl/field.h
@@ -5,6 +5,10 @@
 #ifndef _SECP256K1_FIELD_IMPL_H_
 #define _SECP256K1_FIELD_IMPL_H_
 
+#if defined HAVE_CONFIG_H
+#include "libsecp256k1-config.h"
+#endif
+
 #if defined(USE_FIELD_GMP)
 #include "field_gmp.h"
 #elif defined(USE_FIELD_10X26)
diff --git a/src/impl/field_5x52.h b/src/impl/field_5x52.h
index 5347189f1..b9b2be20e 100644
--- a/src/impl/field_5x52.h
+++ b/src/impl/field_5x52.h
@@ -5,6 +5,10 @@
 #ifndef _SECP256K1_FIELD_REPR_IMPL_H_
 #define _SECP256K1_FIELD_REPR_IMPL_H_
 
+#if defined HAVE_CONFIG_H
+#include "libsecp256k1-config.h"
+#endif
+
 #include <assert.h>
 #include <string.h>
 #include "../num.h"
diff --git a/src/impl/num.h b/src/impl/num.h
index fc6d05c3d..95b124097 100644
--- a/src/impl/num.h
+++ b/src/impl/num.h
@@ -5,6 +5,10 @@
 #ifndef _SECP256K1_NUM_IMPL_H_
 #define _SECP256K1_NUM_IMPL_H_
 
+#if defined HAVE_CONFIG_H
+#include "libsecp256k1-config.h"
+#endif
+
 #include "../num.h"
 
 #if defined(USE_NUM_GMP)
diff --git a/src/num.h b/src/num.h
index b2e7462bc..596a1226c 100644
--- a/src/num.h
+++ b/src/num.h
@@ -5,6 +5,10 @@
 #ifndef _SECP256K1_NUM_
 #define _SECP256K1_NUM_
 
+#if defined HAVE_CONFIG_H
+#include "libsecp256k1-config.h"
+#endif
+
 #if defined(USE_NUM_GMP)
 #include "num_gmp.h"
 #elif defined(USE_NUM_OPENSSL)
diff --git a/src/tests.c b/src/tests.c
index af7bbaad0..be34dfadb 100644
--- a/src/tests.c
+++ b/src/tests.c
@@ -2,6 +2,10 @@
 // Distributed under the MIT/X11 software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+#if defined HAVE_CONFIG_H
+#include "libsecp256k1-config.h"
+#endif
+
 #include <assert.h>
 
 #include "impl/num.h"