diff --git a/src/libCom/osi/os/WIN32/osdThread.c b/src/libCom/osi/os/WIN32/osdThread.c
index 07668308d..b7f50d7f0 100644
--- a/src/libCom/osi/os/WIN32/osdThread.c
+++ b/src/libCom/osi/os/WIN32/osdThread.c
@@ -369,6 +369,13 @@ epicsShareFunc void epicsShareAPI threadShow(void)
     printf("threadShow not implemented\n");
 }
 
+epicsShareFunc void epicsShareAPI threadOnce(
+    threadOnceId *id, void (*func)(void *), void *arg)
+{
+    printf("threadOnce not implemented\n");
+    cantProceed("threadOnce");
+}
+
 epicsShareFunc threadPrivateId epicsShareAPI threadPrivateCreate ()
 {
     osdThreadPrivate *p = (osdThreadPrivate *) malloc (sizeof (*p));
diff --git a/src/libCom/osi/os/WIN32/osdThread.h b/src/libCom/osi/os/WIN32/osdThread.h
index 8587d6dbc..ad0e74638 100644
--- a/src/libCom/osi/os/WIN32/osdThread.h
+++ b/src/libCom/osi/os/WIN32/osdThread.h
@@ -2,4 +2,6 @@
 #ifndef osdThreadh
 #define osdThreadh
 
+typedef int threadOnceId;
+
 #endif /* osdThreadh */
diff --git a/src/libCom/osi/osiThread.h b/src/libCom/osi/osiThread.h
index 3dea87126..90eab41a4 100644
--- a/src/libCom/osi/osiThread.h
+++ b/src/libCom/osi/osiThread.h
@@ -113,7 +113,8 @@ private:
 
 #include "osdThread.h"
 
-void threadOnce(threadOnceId *id, void (*func)(void *), void *arg);
+epicsShareFunc void epicsShareAPI threadOnce(
+    threadOnceId *id, void (*func)(void *), void *arg);
 
 #ifdef __cplusplus