diff --git a/src/iconv.cr b/src/iconv.cr
index 14d1ddea4b04..f8017969910c 100644
--- a/src/iconv.cr
+++ b/src/iconv.cr
@@ -1,6 +1,4 @@
-{% if !flag?(:windows) %}
-  require "c/iconv"
-{% end %}
+require "c/iconv"
 
 # :nodoc:
 struct Iconv
@@ -17,6 +15,8 @@ struct Iconv
       end
     {% end %}
 
+    @iconv = uninitialized LibC::IconvT
+
     {% if !flag?(:windows) %}
       @iconv = LibC.iconv_open(to, from)
 
@@ -34,7 +34,6 @@ struct Iconv
         end
       end
     {% end %}
-
   end
 
   def self.new(from : String, to : String, invalid : Symbol? = nil)
diff --git a/src/io.cr b/src/io.cr
index 5b49049f01d0..b1b1920a3883 100644
--- a/src/io.cr
+++ b/src/io.cr
@@ -1029,5 +1029,6 @@ require "./io/error.cr"
 require "./io/fd_set.cr"
 require "./io/file_descriptor.cr"
 require "./io/hexdump.cr"
+require "./io/memory.cr"
 require "./io/multi_writer.cr"
 require "./io/sized.cr"
diff --git a/src/lib_c/x86_64-windows-gnu/c/iconv.cr b/src/lib_c/x86_64-windows-gnu/c/iconv.cr
new file mode 100644
index 000000000000..230d65f69cda
--- /dev/null
+++ b/src/lib_c/x86_64-windows-gnu/c/iconv.cr
@@ -0,0 +1,3 @@
+lib LibC
+  type IconvT = Void*
+end
diff --git a/src/prelude.cr b/src/prelude.cr
index 414af4627708..4aa5e5954b57 100644
--- a/src/prelude.cr
+++ b/src/prelude.cr
@@ -28,16 +28,16 @@ require "char/reader"
 require "class"
 require "concurrent"
 require "deque"
-# require "dir"
+require "dir"
 require "enum"
 require "enumerable"
 require "env"
-# require "errno"
+require "errno"
 require "ext"
 require "file"
 require "float"
 require "gc"
-# # require "gc/null"
+# require "gc/null"
 require "gc/boehm"
 require "hash"
 require "iconv"
@@ -47,7 +47,7 @@ require "io"
 require "kernel"
 require "main"
 require "math/math"
-# require "mutex"
+require "mutex"
 require "named_tuple"
 require "nil"
 require "number"
@@ -61,14 +61,14 @@ require "random"
 require "range"
 require "reference"
 require "reflect"
-# require "regex"
+require "regex"
 require "set"
-# require "signal"
+require "signal"
 require "slice"
 require "static_array"
 require "struct"
 require "symbol"
-# require "system"
+require "system"
 require "thread"
 require "time"
 require "tuple"
diff --git a/src/regex.cr b/src/regex.cr
index bd39d12b5fc4..8464c657447a 100644
--- a/src/regex.cr
+++ b/src/regex.cr
@@ -1,4 +1,6 @@
-require "./regex/*"
+{% if !flag?(:windows) %}
+  require "./regex/*"
+{% end %}
 
 # A Regex represents a regular expression, a pattern that describes the
 # contents of strings. A Regex can determine whether or not a string matches
diff --git a/windows-prelude.cr b/windows-prelude.cr
new file mode 100644
index 000000000000..61db1577a9b8
--- /dev/null
+++ b/windows-prelude.cr
@@ -0,0 +1,66 @@
+require "lib_c"
+require "macros"
+require "object"
+require "comparable"
+require "exception"
+require "iterable"
+require "iterator"
+require "indexable"
+require "string"
+
+require "array"
+require "atomic"
+require "bool"
+require "box"
+require "char"
+require "char/reader"
+require "class"
+require "concurrent"
+require "deque"
+# require "dir"
+require "enum"
+require "enumerable"
+require "env"
+# require "errno"
+require "ext"
+require "file"
+require "float"
+require "gc"
+# # require "gc/null"
+require "gc/boehm"
+require "hash"
+require "iconv"
+require "int"
+require "intrinsics"
+require "io"
+require "kernel"
+require "main"
+require "math/math"
+# require "mutex"
+require "named_tuple"
+require "nil"
+require "number"
+require "pointer"
+require "pretty_print"
+require "primitives"
+require "proc"
+require "process"
+require "raise"
+require "random"
+require "range"
+require "reference"
+require "reflect"
+# require "regex"
+require "set"
+# require "signal"
+require "slice"
+require "static_array"
+require "struct"
+require "symbol"
+# require "system"
+require "thread"
+require "time"
+require "tuple"
+require "unicode"
+require "union"
+require "value"