diff --git a/src/condition.cpp b/src/condition.cpp
index b91a1de4..8e987380 100644
--- a/src/condition.cpp
+++ b/src/condition.cpp
@@ -240,7 +240,7 @@ bool condition::do_timed_wait(const xtime& xt)
     unsigned milliseconds;
     to_duration(xt, milliseconds);
 
-    int res = 0;
+    unsigned int res = 0;
     res = WaitForSingleObject(reinterpret_cast<HANDLE>(m_queue), milliseconds);
     assert(res != WAIT_FAILED && res != WAIT_ABANDONED);
 
diff --git a/src/mutex.cpp b/src/mutex.cpp
index 0cf11199..b82a1b84 100644
--- a/src/mutex.cpp
+++ b/src/mutex.cpp
@@ -89,7 +89,7 @@ void try_mutex::do_lock()
 
 bool try_mutex::do_trylock()
 {
-    int res = 0;
+    unsigned int res = 0;
     res = WaitForSingleObject(reinterpret_cast<HANDLE>(m_mutex), 0);
     assert(res != WAIT_FAILED && res != WAIT_ABANDONED);
     return res == WAIT_OBJECT_0;
@@ -135,7 +135,7 @@ void timed_mutex::do_lock()
 
 bool timed_mutex::do_trylock()
 {
-    int res = 0;
+    unsigned int res = 0;
     res = WaitForSingleObject(reinterpret_cast<HANDLE>(m_mutex), 0);
     assert(res != WAIT_FAILED && res != WAIT_ABANDONED);
     return res == WAIT_OBJECT_0;
@@ -146,7 +146,7 @@ bool timed_mutex::do_timedlock(const xtime& xt)
     unsigned milliseconds;
     to_duration(xt, milliseconds);
 
-    int res = WaitForSingleObject(reinterpret_cast<HANDLE>(m_mutex), milliseconds);
+    unsigned int res = WaitForSingleObject(reinterpret_cast<HANDLE>(m_mutex), milliseconds);
     assert(res != WAIT_FAILED && res != WAIT_ABANDONED);
     return res == WAIT_OBJECT_0;
 }
diff --git a/src/once.cpp b/src/once.cpp
index ac3c443c..89eaf70a 100644
--- a/src/once.cpp
+++ b/src/once.cpp
@@ -38,7 +38,7 @@ static void key_init()
 
 static void do_once()
 {
-    once_callback* cb = reinterpret_cast<once_callback>(pthread_getspecific(key));
+    once_callback* cb = reinterpret_cast<once_callback*>(pthread_getspecific(key));
     (**cb)();
 }
 
diff --git a/src/recursive_mutex.cpp b/src/recursive_mutex.cpp
index d6974258..d9b5e891 100644
--- a/src/recursive_mutex.cpp
+++ b/src/recursive_mutex.cpp
@@ -114,7 +114,7 @@ void recursive_try_mutex::do_lock()
 
 bool recursive_try_mutex::do_trylock()
 {
-    int res = 0;
+    unsigned int res = 0;
     res = WaitForSingleObject(reinterpret_cast<HANDLE>(m_mutex), 0);
     assert(res != WAIT_FAILED && res != WAIT_ABANDONED);
 
@@ -189,7 +189,7 @@ void recursive_timed_mutex::do_lock()
 
 bool recursive_timed_mutex::do_trylock()
 {
-    int res = 0;
+    unsigned int res = 0;
     res = WaitForSingleObject(reinterpret_cast<HANDLE>(m_mutex), 0);
     assert(res != WAIT_FAILED && res != WAIT_ABANDONED);
 
@@ -210,7 +210,7 @@ bool recursive_timed_mutex::do_timedlock(const xtime& xt)
     unsigned milliseconds;
     to_duration(xt, milliseconds);
 
-    int res = 0;
+    unsigned int res = 0;
     res = WaitForSingleObject(reinterpret_cast<HANDLE>(m_mutex), milliseconds);
     assert(res != WAIT_FAILED && res != WAIT_ABANDONED);
 
diff --git a/src/semaphore.cpp b/src/semaphore.cpp
index 37105773..c6087e36 100644
--- a/src/semaphore.cpp
+++ b/src/semaphore.cpp
@@ -18,6 +18,7 @@
 #include "timeconv.inl"
 
 #if defined(BOOST_HAS_WINTHREADS)
+#   define NOMINMAX
 #   include <windows.h>
 #elif defined(BOOST_HAS_PTHREADS)
 #   include <pthread.h>
@@ -68,7 +69,7 @@ bool semaphore::down(const xtime& xt)
 {
     unsigned milliseconds;
     to_duration(xt, milliseconds);
-    int res = 0;
+    unsigned int res = 0;
     res = WaitForSingleObject(reinterpret_cast<HANDLE>(m_sema), milliseconds);
     assert(res != WAIT_FAILED && res != WAIT_ABANDONED);
     return res == WAIT_OBJECT_0;
diff --git a/src/xtime.cpp b/src/xtime.cpp
index 47bb474b..7fb5f0b3 100644
--- a/src/xtime.cpp
+++ b/src/xtime.cpp
@@ -26,7 +26,7 @@ int xtime_get(struct xtime* xtp, int clock_type)
 #if defined(BOOST_HAS_FTIME)
         FILETIME ft;
         GetSystemTimeAsFileTime(&ft);
-        const __int64 TIMESPEC_TO_FILETIME_OFFSET = ((__int64)27111902 << 32) + (__int64)3577643008;
+        const boost::uint64_t TIMESPEC_TO_FILETIME_OFFSET = ((boost::uint64_t)27111902UL << 32) + (boost::uint64_t)3577643008UL;
         xtp->sec = (int)((*(__int64*)&ft - TIMESPEC_TO_FILETIME_OFFSET) / 10000000);
         xtp->nsec = (int)((*(__int64*)&ft - TIMESPEC_TO_FILETIME_OFFSET -
             ((__int64)xtp->sec * (__int64)10000000)) * 100);