diff --git a/src/libCom/osi/os/WIN32/osdThread.c b/src/libCom/osi/os/WIN32/osdThread.c
index 00d0de0d6..d01cdcdfb 100644
--- a/src/libCom/osi/os/WIN32/osdThread.c
+++ b/src/libCom/osi/os/WIN32/osdThread.c
@@ -480,7 +480,7 @@ epicsShareFunc int epicsShareAPI epicsThreadIsSuspended (epicsThreadId id)
  */
 epicsShareFunc void epicsShareAPI epicsThreadSleep ( double seconds )
 {
-    static const double mSecPerSec = 1000;
+    static const unsigned mSecPerSec = 1000;
     DWORD milliSecDelay;
 
     if ( seconds <= 0.0 ) {