diff --git a/spec/compiler/codegen/private_spec.cr b/spec/compiler/codegen/private_spec.cr
index 613d0b0bd162..c2d2452952c7 100644
--- a/spec/compiler/codegen/private_spec.cr
+++ b/spec/compiler/codegen/private_spec.cr
@@ -14,11 +14,9 @@ describe "Codegen: private" do
     ]
     compiler.prelude = "empty"
 
-    output_filename = File.tempname("crystal-spec-output")
-
-    compiler.compile sources, output_filename
-  ensure
-    File.delete(output_filename) if output_filename
+    with_temp_executable "crystal-spec-output" do |output_filename|
+      compiler.compile sources, output_filename
+    end
   end
 
   it "codegens overloaded private def in same file" do
@@ -39,11 +37,9 @@ describe "Codegen: private" do
     ]
     compiler.prelude = "empty"
 
-    output_filename = File.tempname("crystal-spec-output")
-
-    compiler.compile sources, output_filename
-  ensure
-    File.delete(output_filename) if output_filename
+    with_temp_executable "crystal-spec-output" do |output_filename|
+      compiler.compile sources, output_filename
+    end
   end
 
   it "doesn't include filename for private types" do
diff --git a/spec/compiler/compiler_spec.cr b/spec/compiler/compiler_spec.cr
index 6854302095fc..a0e24c795727 100644
--- a/spec/compiler/compiler_spec.cr
+++ b/spec/compiler/compiler_spec.cr
@@ -7,7 +7,7 @@ describe "Compiler" do
   end
 
   it "compiles a file" do
-    with_tempfile "compiler_spec_output" do |path|
+    with_temp_executable "compiler_spec_output" do |path|
       Crystal::Command.run ["build"].concat(program_flags_options).concat([compiler_datapath("compiler_sample"), "-o", path])
 
       File.exists?(path).should be_true
@@ -18,7 +18,7 @@ describe "Compiler" do
 
   it "runs subcommand in preference to a filename " do
     Dir.cd compiler_datapath do
-      with_tempfile "compiler_spec_output" do |path|
+      with_temp_executable "compiler_spec_output" do |path|
         Crystal::Command.run ["build"].concat(program_flags_options).concat(["compiler_sample", "-o", path])
 
         File.exists?(path).should be_true
diff --git a/spec/compiler/util_spec.cr b/spec/compiler/util_spec.cr
new file mode 100644
index 000000000000..9a4815a9e588
--- /dev/null
+++ b/spec/compiler/util_spec.cr
@@ -0,0 +1,20 @@
+require "spec"
+require "compiler/crystal/util"
+
+describe Crystal do
+  describe "normalize_path" do
+    sep = {{ flag?(:win32) ? "\\" : "/" }}
+
+    it { Crystal.normalize_path("a").should eq ".#{sep}a" }
+    it { Crystal.normalize_path("./a/b").should eq ".#{sep}a#{sep}b" }
+    it { Crystal.normalize_path("../a/b").should eq ".#{sep}..#{sep}a#{sep}b" }
+    it { Crystal.normalize_path("/foo/bar").should eq "#{sep}foo#{sep}bar" }
+
+    {% if flag?(:win32) %}
+      it { Crystal.normalize_path("C:\\foo\\bar").should eq "C:\\foo\\bar" }
+      it { Crystal.normalize_path("C:foo\\bar").should eq "C:foo\\bar" }
+      it { Crystal.normalize_path("\\foo\\bar").should eq "\\foo\\bar" }
+      it { Crystal.normalize_path("foo\\bar").should eq ".\\foo\\bar" }
+    {% end %}
+  end
+end
diff --git a/spec/spec_helper.cr b/spec/spec_helper.cr
index 0d17a2118e94..0a67b2f9f802 100644
--- a/spec/spec_helper.cr
+++ b/spec/spec_helper.cr
@@ -4,10 +4,10 @@ ENV["CRYSTAL_PATH"] = "#{__DIR__}/../src"
 
 require "spec"
 
-{% skip_file if flag?(:win32) %}
-
 require "../src/compiler/crystal/**"
 require "./support/syntax"
+require "./support/tempfile"
+require "./support/win32"
 
 class Crystal::Program
   def union_of(type1, type2, type3)
@@ -114,22 +114,23 @@ def assert_no_errors(*args)
   semantic(*args)
 end
 
-def warnings_result(code)
-  output_filename = Crystal.temp_executable("crystal-spec-output")
-
+def warnings_result(code, *, file = __FILE__)
   compiler = create_spec_compiler
   compiler.warnings = Warnings::All
   compiler.error_on_warnings = false
   compiler.prelude = "empty" # avoid issues in the current std lib
   compiler.color = false
   apply_program_flags(compiler.flags)
-  result = compiler.compile Compiler::Source.new("code.cr", code), output_filename
 
-  result.program.warning_failures
+  with_temp_executable("crystal-spec-output", file: file) do |output_filename|
+    result = compiler.compile Compiler::Source.new("code.cr", code), output_filename
+
+    return result.program.warning_failures
+  end
 end
 
 def assert_warning(code, message, *, file = __FILE__, line = __LINE__)
-  warning_failures = warnings_result(code)
+  warning_failures = warnings_result(code, file: file)
   warning_failures.size.should eq(1), file, line
   warning_failures[0].should start_with(message), file, line
 end
@@ -220,7 +221,7 @@ def create_spec_compiler
   compiler
 end
 
-def run(code, filename = nil, inject_primitives = true, debug = Crystal::Debug::None, flags = nil)
+def run(code, filename = nil, inject_primitives = true, debug = Crystal::Debug::None, flags = nil, *, file = __FILE__)
   if inject_primitives
     code = %(require "primitives"\n#{code})
   end
@@ -239,53 +240,24 @@ def run(code, filename = nil, inject_primitives = true, debug = Crystal::Debug::
     ast.expressions[-1] = exps
     code = ast.to_s
 
-    output_filename = Crystal.temp_executable("crystal-spec-output")
-
     compiler = create_spec_compiler
     compiler.debug = debug
     compiler.flags.concat flags if flags
     apply_program_flags(compiler.flags)
-    compiler.compile Compiler::Source.new("spec", code), output_filename
 
-    output = `#{Process.quote(output_filename)}`
-    File.delete(output_filename)
+    with_temp_executable("crystal-spec-output", file: file) do |output_filename|
+      compiler.compile Compiler::Source.new("spec", code), output_filename
 
-    SpecRunOutput.new(output)
+      output = `#{Process.quote(output_filename)}`
+      return SpecRunOutput.new(output)
+    end
   else
     new_program.run(code, filename: filename, debug: debug)
   end
 end
 
-def build(code)
-  code_file = File.tempname("build_and_run_code")
-
-  # write code to the temp file
-  File.write(code_file, code)
-
-  binary_file = File.tempname("build_and_run_bin")
-
-  `bin/crystal build #{encode_program_flags} #{Process.quote(code_file.path.to_s)} -o #{Process.quote(binary_file.path.to_s)}`
-  File.exists?(binary_file).should be_true
-
-  yield binary_file
-ensure
-  File.delete(code_file) if code_file
-  File.delete(binary_file) if binary_file
-end
-
-def build_and_run(code)
-  build(code) do |binary_file|
-    out_io, err_io = IO::Memory.new, IO::Memory.new
-    status = Process.run(binary_file, output: out_io, error: err_io)
-
-    {status, out_io.to_s, err_io.to_s}
-  end
-end
-
-def test_c(c_code, crystal_code)
-  c_filename = "#{__DIR__}/temp_abi.c"
-  o_filename = "#{__DIR__}/temp_abi.o"
-  begin
+def test_c(c_code, crystal_code, *, file = __FILE__)
+  with_tempfile("temp_abi.c", "temp_abi.o", file: file) do |c_filename, o_filename|
     File.write(c_filename, c_code)
 
     `#{Crystal::Compiler::CC} #{Process.quote(c_filename)} -c -o #{Process.quote(o_filename)}`.should be_truthy
@@ -293,11 +265,8 @@ def test_c(c_code, crystal_code)
     yield run(%(
     require "prelude"
 
-    @[Link(ldflags: "#{o_filename}")]
+    @[Link(ldflags: #{o_filename.inspect})]
     #{crystal_code}
     ))
-  ensure
-    File.delete(c_filename)
-    File.delete(o_filename)
   end
 end
diff --git a/spec/std/spec_helper.cr b/spec/std/spec_helper.cr
index faee17463a46..b87590327247 100644
--- a/spec/std/spec_helper.cr
+++ b/spec/std/spec_helper.cr
@@ -1,29 +1,12 @@
 require "spec"
 require "../support/tempfile"
 require "../support/fibers"
+require "../support/win32"
 
 def datapath(*components)
   File.join("spec", "std", "data", *components)
 end
 
-{% if flag?(:win32) %}
-  def pending_win32(description = "assert", file = __FILE__, line = __LINE__, end_line = __END_LINE__, &block)
-    pending("#{description} [win32]", file, line, end_line)
-  end
-
-  def pending_win32(*, describe, file = __FILE__, line = __LINE__, end_line = __END_LINE__, &block)
-    pending_win32(describe, file, line, end_line) { }
-  end
-{% else %}
-  def pending_win32(description = "assert", file = __FILE__, line = __LINE__, end_line = __END_LINE__, &block)
-    it(description, file, line, end_line, &block)
-  end
-
-  def pending_win32(*, describe, file = __FILE__, line = __LINE__, end_line = __END_LINE__, &block)
-    describe(describe, file, line, end_line, &block)
-  end
-{% end %}
-
 private class Witness
   @checked = false
 
@@ -92,8 +75,8 @@ def spawn_and_check(before : Proc(_), file = __FILE__, line = __LINE__, &block :
   end
 end
 
-def compile_file(source_file, flags = %w(--debug))
-  with_tempfile("executable_file") do |executable_file|
+def compile_file(source_file, flags = %w(--debug), file = __FILE__)
+  with_temp_executable("executable_file", file: file) do |executable_file|
     Process.run("bin/crystal", ["build"] + flags + ["-o", executable_file, source_file])
     File.exists?(executable_file).should be_true
 
@@ -101,17 +84,17 @@ def compile_file(source_file, flags = %w(--debug))
   end
 end
 
-def compile_source(source, flags = %w(--debug))
-  with_tempfile("source_file") do |source_file|
+def compile_source(source, flags = %w(--debug), file = __FILE__)
+  with_tempfile("source_file", file: file) do |source_file|
     File.write(source_file, source)
-    compile_file(source_file, flags) do |executable_file|
+    compile_file(source_file, flags, file: file) do |executable_file|
       yield executable_file
     end
   end
 end
 
-def compile_and_run_file(source_file, flags = %w(--debug))
-  compile_file(source_file) do |executable_file|
+def compile_and_run_file(source_file, flags = %w(--debug), file = __FILE__)
+  compile_file(source_file, file: file) do |executable_file|
     output, error = IO::Memory.new, IO::Memory.new
     status = Process.run executable_file, output: output, error: error
 
@@ -119,9 +102,9 @@ def compile_and_run_file(source_file, flags = %w(--debug))
   end
 end
 
-def compile_and_run_source(source, flags = %w(--debug))
-  with_tempfile("source_file") do |source_file|
+def compile_and_run_source(source, flags = %w(--debug), file = __FILE__)
+  with_tempfile("source_file", file: file) do |source_file|
     File.write(source_file, source)
-    compile_and_run_file(source_file, flags)
+    compile_and_run_file(source_file, flags, file: file)
   end
 end
diff --git a/spec/support/tempfile.cr b/spec/support/tempfile.cr
index 4f527e35329c..0c47ee765e90 100644
--- a/spec/support/tempfile.cr
+++ b/spec/support/tempfile.cr
@@ -34,6 +34,15 @@ def with_tempfile(*paths, file = __FILE__)
   end
 end
 
+def with_temp_executable(name, file = __FILE__)
+  {% if flag?(:win32) %}
+    name += ".exe"
+  {% end %}
+  with_tempfile(name, file: file) do |tempname|
+    yield tempname
+  end
+end
+
 if SPEC_TEMPFILE_CLEANUP
   at_exit do
     FileUtils.rm_r(SPEC_TEMPFILE_PATH) if Dir.exists?(SPEC_TEMPFILE_PATH)
diff --git a/spec/support/win32.cr b/spec/support/win32.cr
new file mode 100644
index 000000000000..da82d1ca24c3
--- /dev/null
+++ b/spec/support/win32.cr
@@ -0,0 +1,19 @@
+require "spec"
+
+{% if flag?(:win32) %}
+  def pending_win32(description = "assert", file = __FILE__, line = __LINE__, end_line = __END_LINE__, &block)
+    pending("#{description} [win32]", file, line, end_line)
+  end
+
+  def pending_win32(*, describe, file = __FILE__, line = __LINE__, end_line = __END_LINE__, &block)
+    pending_win32(describe, file, line, end_line) { }
+  end
+{% else %}
+  def pending_win32(description = "assert", file = __FILE__, line = __LINE__, end_line = __END_LINE__, &block)
+    it(description, file, line, end_line, &block)
+  end
+
+  def pending_win32(*, describe, file = __FILE__, line = __LINE__, end_line = __END_LINE__, &block)
+    describe(describe, file, line, end_line, &block)
+  end
+{% end %}
diff --git a/src/compiler/crystal/util.cr b/src/compiler/crystal/util.cr
index fe1ef625cb9c..578396c0c888 100644
--- a/src/compiler/crystal/util.cr
+++ b/src/compiler/crystal/util.cr
@@ -62,10 +62,8 @@ module Crystal
   end
 
   def self.normalize_path(path)
-    path_start = ".#{File::SEPARATOR}"
-    unless path.starts_with?(path_start) || path.starts_with?(File::SEPARATOR)
-      path = path_start + path
-    end
-    path.rstrip(File::SEPARATOR)
+    path = ::Path[path].normalize
+    path = ::Path["."] / path unless path.anchor
+    path.to_s
   end
 end
diff --git a/src/prelude.cr b/src/prelude.cr
index 810e27b395fc..5ccd0f959358 100644
--- a/src/prelude.cr
+++ b/src/prelude.cr
@@ -7,12 +7,6 @@
 # to also add them to `docs_main.cr` if their content needs to
 # appear in the API docs.
 
-private macro no_win(stmt)
-  {% unless flag?(:win32) %}
-    {{stmt}}
-  {% end %}
-end
-
 # This list requires ordered statements
 require "crystal/once"
 require "lib_c"
@@ -57,7 +51,9 @@ require "intrinsics"
 require "io"
 require "kernel"
 require "math/math"
-no_win require "mutex"
+{% unless flag?(:win32) %}
+  require "mutex"
+{% end %}
 require "named_tuple"
 require "nil"
 require "humanize"
@@ -73,7 +69,9 @@ require "range"
 require "reference"
 require "regex"
 require "set"
-no_win require "signal"
+{% unless flag?(:win32) %}
+  require "signal"
+{% end %}
 require "slice"
 require "static_array"
 require "struct"