diff --git a/src/runtime/c/pgf/data.h b/src/runtime/c/pgf/data.h
index 4bd31e47b..760a72211 100644
--- a/src/runtime/c/pgf/data.h
+++ b/src/runtime/c/pgf/data.h
@@ -8,6 +8,10 @@
 
 #include "pgf.h"
 
+#ifdef _WIN32
+#include <windows.h>
+#endif
+
 class PGF_INTERNAL_DECL pgf_error : public std::runtime_error {
 public:
     pgf_error(const char *msg) : std::runtime_error(msg)
diff --git a/src/runtime/c/pgf/db.cxx b/src/runtime/c/pgf/db.cxx
index efd2347dd..dd743600a 100644
--- a/src/runtime/c/pgf/db.cxx
+++ b/src/runtime/c/pgf/db.cxx
@@ -1,18 +1,18 @@
+#include <fcntl.h>
 #include <stdlib.h>
 #include <string.h>
 
+#include "data.h"
+
 #ifndef _WIN32
+
 #include <sys/mman.h>
 #include <unistd.h>
-#include <fcntl.h>
 #include <errno.h>
 #include <pthread.h>
 
 #else
 
-#include <io.h>
-#include <windows.h>
-
 static
 size_t getpagesize()
 {
@@ -24,7 +24,6 @@ size_t getpagesize()
 #define ftruncate _chsize
 #endif
 
-#include "data.h"
 #include "ipc.h"
 
 PGF_INTERNAL __thread unsigned char* current_base __attribute__((tls_model("initial-exec"))) = NULL;
@@ -345,6 +344,7 @@ PgfDB::PgfDB(const char* filepath, int flags, int mode) {
         this->filepath = strdup(filepath);
     }
 
+#ifndef _WIN32
 #ifndef MREMAP_MAYMOVE
     if (fd >= 0) {
         ms = (malloc_state*)
@@ -357,6 +357,7 @@ PgfDB::PgfDB(const char* filepath, int flags, int mode) {
     ms = (malloc_state*)
         mmap(NULL, file_size, PROT_READ | PROT_WRITE, mflags, fd, 0);
 #endif
+
     if (ms == MAP_FAILED || ms == NULL) {
         ms = NULL; // mark that ms is not created.
         ::free((void *) this->filepath);
@@ -364,6 +365,33 @@ PgfDB::PgfDB(const char* filepath, int flags, int mode) {
         close(fd);
         throw pgf_systemerror(code, filepath);
     }
+#else
+    if (fd >= 0) {
+        hMap = CreateFileMapping((HANDLE) _get_osfhandle(fd),
+                                NULL,
+                                PAGE_READWRITE,
+                                HIWORD(file_size), LOWORD(file_size),
+                                NULL);
+        if (hMap != NULL) {
+            ms = (malloc_state*) MapViewOfFile(hMap,
+                                            FILE_MAP_WRITE,
+                                            0,0,file_size);
+        } else {
+            hMap = INVALID_HANDLE_VALUE;
+            ms   = NULL;
+        }
+    } else {
+        hMap = INVALID_HANDLE_VALUE;
+        ms = (malloc_state*) ::malloc(file_size);
+    }
+
+    if (ms == NULL) {
+        ::free((void *) this->filepath);
+        int code = errno;
+        close(fd);
+        throw pgf_systemerror(code, filepath);
+    }
+#endif
 
     try {
         rwlock = ipc_new_file_rwlock(this->filepath, &is_first);
@@ -417,12 +445,21 @@ PgfDB::~PgfDB() {
         size_t size =
             ms->top + chunksize(ptr(ms,ms->top)) + sizeof(size_t);
 
+#ifndef _WIN32
 #ifndef MREMAP_MAYMOVE
         if (fd < 0) {
           ::free(ms);
         } else
 #endif
         munmap(ms,size);
+#else
+        if (fd < 0) {
+            ::free(ms);
+        } else {
+            UnmapViewOfFile(ms);
+            CloseHandle(hMap);
+        }
+#endif
     }
 
     if (fd >= 0)
@@ -940,6 +977,7 @@ object PgfDB::malloc_internal(size_t bytes)
             }
 
             malloc_state* new_ms;
+#ifndef _WIN32
 // OSX mman and mman-win32 do not implement mremap or MREMAP_MAYMOVE
 #ifndef MREMAP_MAYMOVE
             if (fd >= 0) {
@@ -956,6 +994,8 @@ object PgfDB::malloc_internal(size_t bytes)
 #endif
             if (new_ms == MAP_FAILED)
                 throw pgf_systemerror(errno);
+#else
+#endif
 
             ms = new_ms;
             current_base = (unsigned char*) ms;
@@ -1162,6 +1202,7 @@ void PgfDB::sync()
         ms->top + chunksize(ptr(ms,ms->top)) + sizeof(size_t);
 
     int res;
+#ifndef _WIN32
 #ifndef MREMAP_MAYMOVE
     if (current_db->fd < 0) {
       res = 0;
@@ -1170,6 +1211,8 @@ void PgfDB::sync()
     res = msync((void *) ms, size, MS_SYNC | MS_INVALIDATE);
     if (res != 0)
         throw pgf_systemerror(errno);
+#else
+#endif
 }
 
 DB_scope::DB_scope(PgfDB *db, DB_scope_mode m)
diff --git a/src/runtime/c/pgf/db.h b/src/runtime/c/pgf/db.h
index a27730efa..375c3655f 100644
--- a/src/runtime/c/pgf/db.h
+++ b/src/runtime/c/pgf/db.h
@@ -62,6 +62,10 @@ private:
 
     pthread_rwlock_t *rwlock;
 
+#ifdef _WIN32
+    HANDLE hMap;
+#endif
+
     friend class PgfReader;
 
 public:
diff --git a/src/runtime/c/pgf/ipc.cxx b/src/runtime/c/pgf/ipc.cxx
index 8a55154e4..911c63c4b 100644
--- a/src/runtime/c/pgf/ipc.cxx
+++ b/src/runtime/c/pgf/ipc.cxx
@@ -1,10 +1,3 @@
-#include <sys/stat.h>
-#include <sys/mman.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <errno.h>
-#include <pthread.h>
-
 //#define DEBUG_IPC
 
 #ifdef DEBUG_IPC
@@ -27,6 +20,14 @@ void ipc_toomany() {
 #define ipc_toomany() throw pgf_error("Too many open grammars")
 #endif
 
+#ifndef _WIN32
+#include <sys/stat.h>
+#include <sys/mman.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+#include <pthread.h>
+
 #define ptr_t(x) size_t
 #define ptr(o,T)  (o ? (T*) (((uint8_t*) locks) + o) : NULL)
 #define offs(p) (((uint8_t*) p) - ((uint8_t*) locks))
@@ -321,6 +322,20 @@ void ipc_release_file_rwlock(const char* file_path,
 
     pthread_mutex_unlock(&locks->mutex);
 }
+#else
+PGF_INTERNAL_DECL
+pthread_rwlock_t *ipc_new_file_rwlock(const char* file_path,
+                                      bool *is_first)
+{
+    return NULL;
+}
+
+PGF_INTERNAL_DECL
+void ipc_release_file_rwlock(const char* file_path,
+                             pthread_rwlock_t *rwlock)
+{
+}
+#endif
 
 #ifdef DEBUG_IPC
 int main(int argc, char *argv[])
diff --git a/src/runtime/c/pgf/pgf.cxx b/src/runtime/c/pgf/pgf.cxx
index dccd8c394..e5dda5c3d 100644
--- a/src/runtime/c/pgf/pgf.cxx
+++ b/src/runtime/c/pgf/pgf.cxx
@@ -1,6 +1,7 @@
 #include <fcntl.h>
 #include <math.h>
 #include <errno.h>
+#include <io.h>
 
 #include "data.h"
 #include "reader.h"
@@ -81,7 +82,13 @@ PgfDB *pgf_boot_ngf(const char* pgf_path, const char* ngf_path,
     FILE *in = NULL;
 
     PGF_API_BEGIN {
-        db = new PgfDB(ngf_path, O_CREAT | O_EXCL | O_RDWR, S_IRUSR | S_IWUSR);
+        db = new PgfDB(ngf_path, O_CREAT | O_EXCL | O_RDWR,
+#ifndef _WIN32
+         S_IRUSR | S_IWUSR
+#else
+         0
+#endif
+         );
 
         in = fopen(pgf_path, "rb");
         if (!in) {
@@ -160,7 +167,13 @@ PgfDB *pgf_new_ngf(PgfText *abstract_name,
     PgfDB *db = NULL;
 
     PGF_API_BEGIN {
-        db = new PgfDB(fpath, O_CREAT | O_EXCL | O_RDWR, S_IRUSR | S_IWUSR);
+        db = new PgfDB(fpath, O_CREAT | O_EXCL | O_RDWR,
+#ifndef _WIN32
+         S_IRUSR | S_IWUSR
+#else
+         0
+#endif
+);
 
         {
             DB_scope scope(db, WRITER_SCOPE);
diff --git a/src/runtime/c/pgf/pgf.h b/src/runtime/c/pgf/pgf.h
index 9bb0c0e06..9a35cc383 100644
--- a/src/runtime/c/pgf/pgf.h
+++ b/src/runtime/c/pgf/pgf.h
@@ -7,11 +7,11 @@
 #define EXTERN_C
 #endif
 
-#if defined(_MSC_VER)
+#if defined(_MSC_VER) || defined(__MINGW32__)
 
 #if defined(COMPILING_PGF)
-#define PGF_API_DECL __declspec(dllexport) EXTERN_C
-#define PGF_API      __declspec(dllexport) EXTERN_C
+#define PGF_API_DECL EXTERN_C __declspec(dllexport)
+#define PGF_API      EXTERN_C __declspec(dllexport)
 #else
 #define PGF_API_DECL __declspec(dllimport)
 #define PGF_API      ERROR_NOT_COMPILING_LIBPGF
@@ -19,14 +19,6 @@
 #define PGF_INTERNAL_DECL
 #define PGF_INTERNAL
 
-#elif defined(__MINGW32__)
-
-#define PGF_API_DECL EXTERN_C
-#define PGF_API      EXTERN_C
-
-#define PGF_INTERNAL_DECL
-#define PGF_INTERNAL
-
 #else
 
 #define PGF_API_DECL EXTERN_C
@@ -37,7 +29,7 @@
 
 #endif
 
-#include<stdint.h>
+#include <stdint.h>
 #include <sys/types.h>
 
 #define PGF_MAJOR_VERSION 2
@@ -259,7 +251,7 @@ PgfDB *pgf_read_ngf(const char* fpath,
  * Aside from the name, the grammar is otherwise empty but can be later
  * populated with new functions and categories. If fpath is NULL then
  * the file is not stored on the disk but only in memory. */
-PGF_API
+PGF_API_DECL
 PgfDB *pgf_new_ngf(PgfText *abstract_name,
                    const char *fpath,
                    PgfRevision *revision,
@@ -289,7 +281,7 @@ PGF_API_DECL
 void pgf_iter_categories(PgfDB *db, PgfRevision revision,
                          PgfItor *itor, PgfExn *err);
 
-PGF_API
+PGF_API_DECL
 void pgf_iter_concretes(PgfDB *db, PgfRevision revision,
                         PgfItor *itor, PgfExn *err);