diff --git a/src/libCom/osi/os/RTEMS/osdThread.c b/src/libCom/osi/os/RTEMS/osdThread.c
index 810b29c97..3b2e8ce7d 100644
--- a/src/libCom/osi/os/RTEMS/osdThread.c
+++ b/src/libCom/osi/os/RTEMS/osdThread.c
@@ -657,6 +657,7 @@ void epicsThreadShowAll (unsigned int level)
 
 double epicsThreadSleepQuantum ( void )
 {
-     return 1.0 / rtemsTicksPerSecond_double;
-}
+    extern double rtemsTicksPerSecond_double;
 
+    return 1.0 / rtemsTicksPerSecond_double;
+}