diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3c85a01..f5d1f7a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -177,6 +177,7 @@ IF(WIN32)
   GET_CURRENT_YEAR(CURRENT_YEAR)
   MESSAGE("Year for copyright is " ${CURRENT_YEAR})
 
+  SET(prefix ${CMAKE_INSTALL_PREFIX})
   SET(RC_COMMENT "${PACKAGE_NAME} library")
   SET(RC_INTERNAL_NAME "${PACKAGE_NAME} ${WIN32_MODE}")
   SET(RC_ORIGINAL_NAME ${PACKAGE_NAME}.dll)
diff --git a/contrib/win32/stdlib.c b/contrib/win32/stdlib.c
index 95e3a1d..fc27042 100644
--- a/contrib/win32/stdlib.c
+++ b/contrib/win32/stdlib.c
@@ -34,21 +34,24 @@
 // Handle platform specific includes
 #include "contrib/windows.h"
 
+//There is no setenv()and unsetenv() in windows,but we can use putenv() instead.
 int setenv(const char *name, const char *value, int overwrite)
 {
-  int exists = GetEnvironmentVariableA(name, NULL, 0);
-  if ((exists && overwrite) || (!exists)) {
-    if (!SetEnvironmentVariableA(name, value)) {
-      // Set errno here correctly
-      return -1;
-    }
-    return 0;
+  char* env = getenv(name);
+  if ((env && overwrite) || (!env)) {
+    char* str[32];
+    strcpy(str,name);
+    strcat(str,"=");
+    strcat(str,value);
+    return putenv(str);
   }
-  // Exists and overwrite is 0.
   return -1;
 }
 
 void unsetenv(const char *name)
 {
-  SetEnvironmentVariableA(name, NULL);
+  char* str[32];
+  strcpy(str,name);
+  strcat(str,"=");
+  putenv(str);
 }