diff --git a/.gitmodules b/.gitmodules
index 779ec4875e9d74d3b4eef45f6349e551c3258339..cb5a4e231848994b7d000813df14d87155613ece 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +1,6 @@
 [submodule "pyopencl/compyte"]
 	path = pyopencl/compyte
 	url = https://github.com/inducer/compyte
+[submodule "src/c_wrapper/mingw-std-threads"]
+	path = src/c_wrapper/mingw-std-threads
+	url = https://github.com/meganz/mingw-std-threads.git
diff --git a/MANIFEST.in b/MANIFEST.in
index 27620315df94c908997e2ebfcd1748144a3f81e0..b04caf8b64c87d4469166559989695921e684050 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -4,6 +4,7 @@ include pyopencl/cl/*.cl
 include src/c_wrapper/*.hpp
 include src/c_wrapper/*.h
 include src/c_wrapper/*.cpp
+include src/c_wrapper/mingw-std-wrappers/mingw.*.h
 include *.h
 include test/*.py
 include test/*.h
diff --git a/pyopencl/cffi_cl.py b/pyopencl/cffi_cl.py
index f2c9206378a2b898ad0602905d743ce7469a2c29..a4ba6e41595825ccea3c56965fc19e33308a87fc 100644
--- a/pyopencl/cffi_cl.py
+++ b/pyopencl/cffi_cl.py
@@ -35,7 +35,8 @@ import sys
 from pyopencl._cffi import ffi as _ffi
 from .compyte.array import f_contiguous_strides, c_contiguous_strides
 
-_lib = _ffi.dlopen(None)
+
+from pyopencl._cffi import lib as _lib
 
 
 class _CLKernelArg(object):
@@ -456,7 +457,8 @@ class migrate_mem_object_flags_ext(_NoInit):  # noqa
 _locals = locals()
 
 
-@_ffi.callback('void (*)(const char*, const char* name, long value)')
+# TODO: constant values are cl_ulong
+@_ffi.callback('void (*)(const char*, const char* name, unsigned long value)')
 def _constant_callback(type_, name, value):
     setattr(_locals[_ffi_pystr(type_)], _ffi_pystr(name), value)  # noqa
 
diff --git a/src/c_wrapper/debug.h b/src/c_wrapper/debug.h
index c5616587058bcd4a3784cfe7a97ce73401aed5b9..d314da4ff8ae12f63a557697385e45bc89944e23 100644
--- a/src/c_wrapper/debug.h
+++ b/src/c_wrapper/debug.h
@@ -1,8 +1,18 @@
 #include "wrap_cl.h"
 #include "function.h"
 #include <string.h>
+
+#ifdef __MINGW32__
+
+#include "mingw-std-threads/mingw.mutex.h"
+#include "mingw-std-threads/mingw.thread.h"
+
+#else
+
 #include <mutex>
 
+#endif
+
 #ifndef __PYOPENCL_DEBUG_H
 #define __PYOPENCL_DEBUG_H
 
diff --git a/src/c_wrapper/mingw-std-threads b/src/c_wrapper/mingw-std-threads
new file mode 160000
index 0000000000000000000000000000000000000000..776ce7faf9368ec9588ee77458799c281cb25737
--- /dev/null
+++ b/src/c_wrapper/mingw-std-threads
@@ -0,0 +1 @@
+Subproject commit 776ce7faf9368ec9588ee77458799c281cb25737
diff --git a/src/c_wrapper/wrap_cl_core.h b/src/c_wrapper/wrap_cl_core.h
index 9f4c751fa666e56d04416e3f5de407e6d07f0b56..0cae572ab211743350a9ad05ac22ecf0226b5027 100644
--- a/src/c_wrapper/wrap_cl_core.h
+++ b/src/c_wrapper/wrap_cl_core.h
@@ -56,7 +56,7 @@ void set_py_funcs(int (*_gc)(), void *(*_ref)(void*), void (*_deref)(void*),
 int have_gl();
 
 unsigned bitlog2(unsigned long v);
-void populate_constants(void(*add)(const char*, const char*, long value));
+void populate_constants(void(*add)(const char*, const char*, unsigned long value));
 int get_debug();
 void set_debug(int debug);
 
diff --git a/src/c_wrapper/wrap_constants.cpp b/src/c_wrapper/wrap_constants.cpp
index 1ac31e15c7291e798463ef503448abc3ae9dcf11..952d3b51b063529d7f3d603f0f9fac68fbf9e77f 100644
--- a/src/c_wrapper/wrap_constants.cpp
+++ b/src/c_wrapper/wrap_constants.cpp
@@ -2,7 +2,7 @@
 #include <iostream>
 
 extern "C"
-void populate_constants(void(*add)(const char*, const char*, long value))
+void populate_constants(void(*add)(const char*, const char*, unsigned long value))
 {
 #define _ADD_ATTR(TYPE, PREFIX, NAME, SUFFIX, ...)      \
       add(TYPE, #NAME, CL_##PREFIX##NAME##SUFFIX)