diff --git a/.gitignore b/.gitignore
index fc8db16..e024c8d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,5 @@
 c_src/*.o
 c_src/*/*.o
-.eunit
-ebin/
 priv/*.so
+_build
+rebar.lock
diff --git a/Makefile b/Makefile
index 565c7b5..47052d8 100644
--- a/Makefile
+++ b/Makefile
@@ -1,10 +1,11 @@
 all:
-	./rebar -v get-deps
-	./rebar -v compile
+	./rebar3 compile
 
 clean:
-	./rebar -v delete-deps
-	./rebar -v clean
+	./rebar3 clean
+
+clean-deps: clean
+	rm -rf _build
 
 eunit:
-	./rebar -v eunit
+	./rebar3 eunit
diff --git a/c_src/Makefile b/c_src/Makefile
new file mode 100644
index 0000000..cc8d452
--- /dev/null
+++ b/c_src/Makefile
@@ -0,0 +1,82 @@
+# Based on c_src.mk from erlang.mk by Loic Hoguin <essen@ninenines.eu>
+
+CURDIR := $(shell pwd)
+BASEDIR := $(abspath $(CURDIR)/..)
+
+PROJECT ?= $(notdir $(BASEDIR))
+PROJECT := $(strip $(PROJECT))
+
+ERTS_INCLUDE_DIR ?= $(shell erl -noshell -s init stop -eval "io:format(\"~ts/erts-~ts/include/\", [code:root_dir(), erlang:system_info(version)]).")
+ERL_INTERFACE_INCLUDE_DIR ?= $(shell erl -noshell -s init stop -eval "io:format(\"~ts\", [code:lib_dir(erl_interface, include)]).")
+ERL_INTERFACE_LIB_DIR ?= $(shell erl -noshell -s init stop -eval "io:format(\"~ts\", [code:lib_dir(erl_interface, lib)]).")
+
+C_SRC_DIR = $(CURDIR)
+C_SRC_OUTPUT ?= $(CURDIR)/../priv/sha3_nifs.so
+
+# System type and C compiler/flags.
+
+UNAME_SYS := $(shell uname -s)
+ifeq ($(UNAME_SYS), Darwin)
+	CC ?= cc
+	CFLAGS ?= -O3 -std=c99 -arch x86_64 -finline-functions -Wall
+	CXXFLAGS ?= -O3 -arch x86_64 -finline-functions -Wall
+	LDFLAGS ?= -arch x86_64 -flat_namespace -undefined suppress
+else ifeq ($(UNAME_SYS), FreeBSD)
+	CC ?= cc
+	CFLAGS ?= -O3 -std=c99 -finline-functions -Wall
+	CXXFLAGS ?= -O3 -finline-functions -Wall
+else ifeq ($(UNAME_SYS), Linux)
+	CC ?= gcc
+	CFLAGS ?= -O3 -std=c99 -finline-functions -Wall
+	CXXFLAGS ?= -O3 -finline-functions -Wall
+	LDFLAGS ?= -lstdc++
+endif
+
+UNAME_ARCH := $(shell uname -m)
+ifeq ($(UNAME_ARCH), x86_64)
+    C_OPT_SRC_DIR := $(CURDIR)/opt64
+else ifeq ($(UNAME_ARCH), i368)
+    C_OPT_SRC_DIR := $(CURDIR)/opt32
+endif
+
+CFLAGS += -fPIC -I $(ERTS_INCLUDE_DIR) -I $(ERL_INTERFACE_INCLUDE_DIR)
+CXXFLAGS += -fPIC -I $(ERTS_INCLUDE_DIR) -I $(ERL_INTERFACE_INCLUDE_DIR)
+
+LDLIBS += -L $(ERL_INTERFACE_LIB_DIR) -lei
+LDFLAGS += -shared
+
+# Verbosity.
+
+c_verbose_0 = @echo " C     " $(?F);
+c_verbose = $(c_verbose_$(V))
+
+cpp_verbose_0 = @echo " CPP   " $(?F);
+cpp_verbose = $(cpp_verbose_$(V))
+
+link_verbose_0 = @echo " LD    " $(@F);
+link_verbose = $(link_verbose_$(V))
+
+SOURCES := $(shell find $(C_SRC_DIR) $(C_OPT_SRC_DIR) -maxdepth 1 -type f \( -name "*.c" -o -name "*.C" -o -name "*.cc" -o -name "*.cpp" \))
+OBJECTS = $(addsuffix .o, $(basename $(SOURCES)))
+
+COMPILE_C = $(c_verbose) $(CC) $(CFLAGS) $(CPPFLAGS) -c
+COMPILE_CPP = $(cpp_verbose) $(CXX) $(CXXFLAGS) $(CPPFLAGS) -c
+
+$(C_SRC_OUTPUT): $(OBJECTS)
+	@mkdir -p $(BASEDIR)/priv/
+	$(link_verbose) $(CC) $(OBJECTS) $(LDFLAGS) $(LDLIBS) -o $(C_SRC_OUTPUT)
+
+%.o: %.c
+	$(COMPILE_C) $(OUTPUT_OPTION) $<
+
+%.o: %.cc
+	$(COMPILE_CPP) $(OUTPUT_OPTION) $<
+
+%.o: %.C
+	$(COMPILE_CPP) $(OUTPUT_OPTION) $<
+
+%.o: %.cpp
+	$(COMPILE_CPP) $(OUTPUT_OPTION) $<
+
+clean:
+	@rm -f $(C_SRC_OUTPUT) $(OBJECTS)
diff --git a/rebar b/rebar
deleted file mode 100755
index a6df7dc..0000000
Binary files a/rebar and /dev/null differ
diff --git a/rebar.config b/rebar.config
index 8c37b0f..c132e05 100644
--- a/rebar.config
+++ b/rebar.config
@@ -3,28 +3,11 @@
 {erl_opts, [warnings_as_errors]}.
 
 {deps, [
-        {hex, ".*", {git, "git://github.com/b/hex", "HEAD"}}
-       ]}.
-
-{port_specs, [
-              {"-32-unix$", "priv/sha3_nifs.so", ["c_src/*.c", "c_src/opt32/*.c"]},
-              {"-64-unix$", "priv/sha3_nifs.so", ["c_src/*.c", "c_src/opt64/*.c"]}
-              ]}.
-
-{port_env, [
-             %% Make sure to link -lstdc++ on linux or solaris
-             {"(linux|solaris)", "CXXFLAGS", "-O2"},
-             {"(linux|solaris)", "LDFLAGS", "$LDFLAGS -lstdc++"},
-
-             %% OS X Leopard flags for 64-bit
-             {"darwin9\.*-64-unix", "CXXFLAGS", "-O2 -m64"},
-             {"darwin9\.*-64-unix", "LDFLAGS", "-arch x86_64 -lstdc++"},
-
-             %% OS X Snow Leopard flags for 32-bit
-             {"darwin1?\.*-32-unix", "CXXFLAGS", "-O2 -m32"},
-             {"darwin1?\.*-32-unix", "LDFLAGS", "-arch i386"},
-
-             %% OS X Snow Leopard/Lion flags for 64-bit
-             {"darwin1?\.*-64-unix", "CXXFLAGS", "-O2 -m64"},
-             {"darwin1?\.*-64-unix", "LDFLAGS", "-arch x86_64"}
-             ]}.
+  {hex, ".*", {git, "https://github.com/b/hex.git", "HEAD"}}
+]}.
+{pre_hooks,
+  [{"(linux|darwin|solaris)", compile, "make -C c_src"},
+    {"(freebsd)", compile, "gmake -C c_src"}]}.
+{post_hooks,
+  [{"(linux|darwin|solaris)", clean, "make -C c_src clean"},
+    {"(freebsd)", clean, "gmake -C c_src clean"}]}.
diff --git a/rebar3 b/rebar3
new file mode 100755
index 0000000..7e102d6
Binary files /dev/null and b/rebar3 differ
diff --git a/test/sha3_tests.erl b/test/sha3_tests.erl
index 24cf928..1e9752b 100644
--- a/test/sha3_tests.erl
+++ b/test/sha3_tests.erl
@@ -40,7 +40,7 @@ parse_triples([Len, Msg, Md|Lines], Acc) ->
 
 msgkat(Set, Bits, Fun) ->
     {ok, Cwd} = file:get_cwd(),
-    Filename = filename:join([Cwd, "..", "test", "data", Set ++ "MsgKAT.zip"]),
+    Filename = filename:join([Cwd, "test", "data", Set ++ "MsgKAT.zip"]),
     {ok, ZipHandle} = zip:zip_open(Filename, [memory]),
     {ok, {_, Data}} = zip:zip_get(Set ++ "MsgKAT_" ++ integer_to_list(Bits) ++ ".txt", ZipHandle),
     Lines = lists:filter(