diff --git a/ext/duk_config.h b/ext/duk_config.h
index c88180d..a8362ec 100644
--- a/ext/duk_config.h
+++ b/ext/duk_config.h
@@ -2900,6 +2900,27 @@ typedef struct duk_hthread duk_context;
 #undef DUK_USE_COMPILER_STRING
 #define DUK_USE_COMPILER_STRING "crystal/llvm"
 
+#if defined(WIN32) || defined(_WIN32) || defined(__WIN32)
+int gettimeofday(struct timeval *tp, struct timezone *tzp)
+{
+    static const uint64_t EPOCH = ((uint64_t) 116444736000000000ULL);
+
+    SYSTEMTIME system_time;
+    FILETIME file_time;
+    uint64_t time;
+
+    GetSystemTime(&system_time);
+    SystemTimeToFileTime(&system_time, &file_time);
+    time = ((uint64_t) file_time.dwLowDateTime);
+    time += ((uint64_t) file_time.dwHighDateTime) << 32;
+
+    tp->tv_sec = (long) ((time - EPOCH) / 10000000L);
+    tp->tv_usec = (long) (system_time.wMilliseconds * 1000);
+
+    return 0;
+}
+#endif
+
 #define DUK_USE_EXEC_TIMEOUT_CHECK duk_cr_timeout
 struct timeout_data {
   struct timeval start;
diff --git a/ext/justfile b/ext/justfile
new file mode 100644
index 0000000..9a4f3f6
--- /dev/null
+++ b/ext/justfile
@@ -0,0 +1,49 @@
+set shell := ["bash", "-uc"]
+set windows-shell := ["cmd.exe", "/c"]
+
+cc := if os() == "windows" {
+    if `where gcc 2>NUL || exit 0` == "" {
+        if `where clang 2>NUL || exit 0` == "" {
+            error("cannot find C compiler")
+        } else {
+            trim(replace(`where clang`, "\\", "\\\\"))
+        }
+    } else {
+        replace(`where gcc`, "\\", "\\\\")
+    }
+} else {
+    "cc"
+}
+
+cflags := "-pedantic -c -std=c99 -O2 -fstrict-aliasing -fomit-frame-pointer"
+current := justfile_directory()
+output := join(current, "..", "src", ".build")
+
+[unix]
+build:
+    mkdir -p {{output}}
+    {{cc}} -o {{output}}/libduktape.o {{current}}/duktape.c {{cflags}}
+
+    mkdir -p {{output}}/lib
+    ar rcs {{output}}/lib/libduktape.a {{output}}/libduktape.o
+
+    mkdir -p {{output}}/include
+    cp {{current}}/duktape.h {{current}}/duk_config.h {{output}}/include
+
+[windows]
+build compiler="{{cc}}":
+    mkdir {{output}}\lib
+    {{compiler}} -o {{output}}\lib\duktape.lib {{current}}\duktape.c {{cflags}} -fuse-ld=llvm-lib
+
+    mkdir {{output}}\include
+    copy {{current}}\duktape.h + {{current}}\duk_config.h {{output}}\include
+
+[unix]
+clean:
+    -rm -rf {{output}}
+    -rm -rf {{current}}/.crystal
+
+[windows]
+clean:
+    -rmdir /q /s {{output}}
+    -rmdir /q /s {{current}}\.crystal
diff --git a/justfile b/justfile
new file mode 100644
index 0000000..a56b925
--- /dev/null
+++ b/justfile
@@ -0,0 +1,49 @@
+set shell := ["bash", "-uc"]
+set windows-shell := ["cmd.exe", "/c"]
+
+current := invocation_directory()
+crystal := if os() == "windows" { trim(`where crystal`) } else { trim(`which crystal`) }
+
+default:
+    @just build
+
+[unix]
+all_spec output="{{current}}\\.build":
+    -mkdir -p {{current}}/.build
+    {{crystal}} build -o {{output}} spec/all_spec.cr --warnings all
+
+[windows]
+all_spec output="{{current}}/.build":
+    -mkdir {{current}}\.build
+    {{crystal}} build -o {{output}} spec\all_spec.cr --warnings all
+
+[unix]
+build output=".build/duktape":
+    -mkdir -p {{current}}/.build
+    {{crystal}} build -o {{output}} src/duktape.cr --warnings all
+
+[windows]
+build output=".build\\duktape":
+    -mkdir {{current}}\.build
+    {{crystal}} build -o {{output}} src\duktape.cr --warnings all
+
+[unix]
+clean:
+    -rm -rf {{current}}/.build
+    -rm -rf {{current}}/.crystal
+
+[windows]
+clean:
+    -rmdir /q /s {{current}}\.build
+    -rmdir /q /s {{current}}\.crystal
+
+cleanlib:
+    @just -f {{current}}/ext/justfile clean
+    make -C {{current}}/ext -f Makefile.internal clean
+
+libduktape:
+    cd ext
+    @just -f ext/justfile build
+
+update:
+    make -C {{current}}/ext -f Makefile.internal update-duktape
diff --git a/shard.yml b/shard.yml
index da25acc..f384fcd 100644
--- a/shard.yml
+++ b/shard.yml
@@ -5,11 +5,11 @@ authors:
   - Jesse Doyle <jdoyle@ualberta.ca>
 
 scripts:
-  postinstall: "make -C ext clean libduktape"
+  postinstall: make -C clean libduktape
 
 development_dependencies:
   ameba:
-    github: veelenga/ameba
+    github: crystal-ameba/ameba
     version: '~> 1.4'
 
 crystal: '>= 0.35.1'
diff --git a/src/lib_duktape.cr b/src/lib_duktape.cr
index f5cc8e2..8994146 100644
--- a/src/lib_duktape.cr
+++ b/src/lib_duktape.cr
@@ -4,7 +4,24 @@
 #
 # This is free software. Please see LICENSE for details.
 
-@[Link(ldflags: "-L#{__DIR__}/.build/lib -L#{__DIR__}/.build/include -lduktape -lm")]
+{% if flag?(:win32) %}
+  lib LibC
+    alias SusecondsT = LongLong
+
+    struct Timeval
+      tv_sec : TimeT
+      tv_usec : SusecondsT
+    end
+
+    fun gettimeofday(tp : Timeval*, timezone : Void*) : Int
+  end
+{% end %}
+
+{% if flag?(:win32) %}
+  @[Link(ldflags: "#{__DIR__}\\.build\\lib\\duktape.lib")]
+{% else %}
+  @[Link(ldflags: "-L#{__DIR__}/.build/lib -L#{__DIR__}/.build/include -lduktape -lm")]
+{% end %}
 lib LibDUK
   alias Context = Void*
   alias Size = LibC::SizeT