diff --git a/ChangeLog b/ChangeLog
index 7ee4050a5..69ecd603e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -7,6 +7,7 @@ Security
      crash it remotely (found by Caj Larsson).
 
 Bugfix
+   * Fix warnings from mingw64 in timing.c (found by kxjklele).
    * Fix potential unintended sign extension in asn1_get_len() on 64-bit
      platforms (found with Coverity Scan).
 
diff --git a/include/polarssl/timing.h b/include/polarssl/timing.h
index 163477406..2f59f0c17 100644
--- a/include/polarssl/timing.h
+++ b/include/polarssl/timing.h
@@ -55,6 +55,10 @@ unsigned long get_timer( struct hr_time *val, int reset );
  * \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 13dc924bb..1ba02fec1 100644
--- a/library/timing.c
+++ b/library/timing.c
@@ -229,20 +229,24 @@ unsigned long get_timer( struct hr_time *val, int reset )
     return( delta );
 }
 
-DWORD WINAPI TimerProc( LPVOID uElapse )
-{   
-    Sleep( (DWORD) uElapse );
-    alarmed = 1; 
+/* It's OK to use a global because alarm() is supposed to be global anyway */
+static DWORD alarmMs;
+
+static DWORD WINAPI TimerProc( LPVOID TimerContext )
+{
+    ((void) TimerContext);
+    Sleep( alarmMs );
+    alarmed = 1;
     return( TRUE );
 }
 
 void set_alarm( int seconds )
-{   
+{
     DWORD ThreadId;
 
-    alarmed = 0; 
-    CloseHandle( CreateThread( NULL, 0, TimerProc,
-        (LPVOID) ( seconds * 1000 ), 0, &ThreadId ) );
+    alarmed = 0;
+    alarmMs = seconds * 1000;
+    CloseHandle( CreateThread( NULL, 0, TimerProc, NULL, 0, &ThreadId ) );
 }
 
 void m_sleep( int milliseconds )