diff --git a/ChangeLog b/ChangeLog
index c545667..2791758 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -9,6 +9,7 @@
 Bugfix
    * Fix hardclock() (only used in the benchmarking program) with some
      versions of mingw64 (found by kxjhlele).
+   * Fix warnings from mingw64 in timing.c (found by kxjklele).
 
 Changes
    * Move from SHA-1 to SHA-256 in example programs using signatures
diff --git a/include/polarssl/timing.h b/include/polarssl/timing.h
index a3eb510..5f3acfa 100644
--- a/include/polarssl/timing.h
+++ b/include/polarssl/timing.h
@@ -65,6 +65,10 @@
  * \brief          Setup an alarm clock
  *
  * \param seconds  delay before the "alarmed" flag is set
+ *
+ * \warning        Only one alarm at a time  is supported. In a threaded
+ *                 context, this means one for the whole process, not one per
+ *                 thread.
  */
 void set_alarm( int seconds );
 
diff --git a/library/timing.c b/library/timing.c
index a612208..913cbdc 100644
--- a/library/timing.c
+++ b/library/timing.c
@@ -251,9 +251,13 @@
     return( delta );
 }
 
-DWORD WINAPI TimerProc( LPVOID uElapse )
+/* It's OK to use a global because alarm() is supposed to be global anyway */
+static DWORD alarmMs;
+
+DWORD WINAPI TimerProc( LPVOID TimerContext )
 {
-    Sleep( (DWORD) uElapse );
+    ((void) TimerContext);
+    Sleep( alarmMs );
     alarmed = 1;
     return( TRUE );
 }
@@ -263,8 +267,8 @@
     DWORD ThreadId;
 
     alarmed = 0;
-    CloseHandle( CreateThread( NULL, 0, TimerProc,
-        (LPVOID) ( seconds * 1000 ), 0, &ThreadId ) );
+    alarmMs = seconds * 1000;
+    CloseHandle( CreateThread( NULL, 0, TimerProc, NULL, 0, &ThreadId ) );
 }
 
 void m_sleep( int milliseconds )