diff --git a/hgdriver/hgdev/hg_ipc.cpp b/hgdriver/hgdev/hg_ipc.cpp
index d02bb0d..e6f0e2a 100644
--- a/hgdriver/hgdev/hg_ipc.cpp
+++ b/hgdriver/hgdev/hg_ipc.cpp
@@ -347,7 +347,7 @@ int shared_memory::write(const char* data, size_t len)
 /////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 // tiny_file_map ...
 #ifdef WIN32
-#define IS_VALID_MAP(map)	!map
+#define IS_VALID_MAP(map)	map
 #else
 #define IS_VALID_MAP(map)	map != -1
 #endif
@@ -406,10 +406,10 @@ int tiny_file_map::open(const char* file, unsigned int size, bool readonly)
 			DWORD wrote = SetFilePointer(f, size - 1, NULL, FILE_BEGIN);
 			if (wrote == size - 1)
 				WriteFile(f, "\0", 1, &wrote, NULL);
-			map_ = CreateFileMappingA(f, NULL, PAGE_READONLY, 0, size, NULL);
+			map_ = CreateFileMappingA(f, NULL, PAGE_READWRITE, 0, size, NULL);
 			if (map_)
 			{
-				buf_ = (unsigned char*)MapViewOfFile(map_, FILE_MAP_READ, 0, 0, size);
+				buf_ = (unsigned char*)MapViewOfFile(map_, FILE_MAP_READ | FILE_MAP_WRITE, 0, 0, size);
 				if (!buf_)
 					ret = GetLastError();
 			}