diff --git a/psycopg/config.h b/psycopg/config.h
index f8e17a9a..95d428a9 100644
--- a/psycopg/config.h
+++ b/psycopg/config.h
@@ -140,6 +140,8 @@ static int pthread_mutex_init(pthread_mutex_t *mutex, void* fake)
 #endif
 #define strcasecmp(x, y) lstrcmpi(x, y)
 #endif
+
+#include "win32_support.h"
 #endif
 
 /* what's this, we have no round function either? */
diff --git a/psycopg/win32_support.c b/psycopg/win32_support.c
index d508b220..7a9c8b88 100644
--- a/psycopg/win32_support.c
+++ b/psycopg/win32_support.c
@@ -35,7 +35,7 @@
    src/port/gettimeofday.c in PostgreSQL core */
 
 /* FILETIME of Jan 1 1970 00:00:00. */
-static const unsigned __int64 epoch = 116444736000000000ULL;
+static const unsigned __int64 epoch = ((unsigned __int64) 116444736000000000ULL);
 
 /*
  * timezone information is stored outside the kernel so tzp isn't used anymore.
@@ -44,7 +44,7 @@ static const unsigned __int64 epoch = 116444736000000000ULL;
  * elapsed_time().
  */
 int
-gettimeofday(struct timeval * tp, struct timezone * tzp)
+gettimeofday(struct timeval * tp, void * tzp)
 {
     FILETIME	file_time;
     SYSTEMTIME	system_time;
@@ -60,17 +60,30 @@ gettimeofday(struct timeval * tp, struct timezone * tzp)
 
     return 0;
 }
+
+/* timeradd missing on MS VC */
+void
+timeradd(struct timeval *a, struct timeval *b, struct timeval *c)
+{
+  c->tv_sec = a->tv_sec + b->tv_sec;
+  c->tv_usec = a->tv_usec + b->tv_usec;
+  if(c->tv_usec >= 1000000L) {
+    c->tv_usec -= 1000000L;
+    c->tv_sec += 1;
+  }
+}
 #endif /* !defined(__MINGW32__) */
 
-/* timersub is missing on mingw */
+/* timersub is missing on mingw & MS VC */
 void
 timersub(struct timeval *a, struct timeval *b, struct timeval *c)
 {
     c->tv_sec  = a->tv_sec  - b->tv_sec;
     c->tv_usec = a->tv_usec - b->tv_usec;
-    if (tv_usec < 0) {
+    if (c->tv_usec < 0) {
         c->tv_usec += 1000000;
         c->tv_sec  -= 1;
     }
 }
+
 #endif /* defined(_WIN32) */
diff --git a/psycopg/win32_support.h b/psycopg/win32_support.h
index be963df5..b463141e 100644
--- a/psycopg/win32_support.h
+++ b/psycopg/win32_support.h
@@ -23,18 +23,26 @@
  * License for more details.
  */
 #ifndef PSYCOPG_WIN32_SUPPORT_H
-#define PSYCOPG_WIN32_SUPPORT_H 1
+#define PSYCOPG_WIN32_SUPPORT_H
 
 #include "psycopg/config.h"
 
+#ifdef _WIN32
+#include <time.h>
+#endif
+#ifdef __MINGW32__
 #include <sys/time.h>
+#endif
+
 
 #ifdef _WIN32
 #ifndef __MINGW32__
-HIDDEN int gettimeofday(struct timeval * tp, struct timezone * tzp);
+extern HIDDEN int gettimeofday(struct timeval * tp, void * tzp);
+extern HIDDEN void timeradd(struct timeval *a, struct timeval *b, struct timeval *c);
+#elif
 #endif
 
-HIDDEN void timersub(struct timeval *a, struct timeval *b, struct timeval *c);
+extern HIDDEN void timersub(struct timeval *a, struct timeval *b, struct timeval *c);
 #endif
 
 #endif /* !defined(PSYCOPG_WIN32_SUPPORT_H) */