diff --git a/src/libCom/osi/os/WIN32/osdThread.c b/src/libCom/osi/os/WIN32/osdThread.c
index b20a3458a..48cd8cb4e 100644
--- a/src/libCom/osi/os/WIN32/osdThread.c
+++ b/src/libCom/osi/os/WIN32/osdThread.c
@@ -98,7 +98,7 @@ static const int osdRealtimePriorityList [osdRealtimePriorityStateCount] =
 
 #if defined(EPICS_BUILD_DLL)
 BOOL WINAPI DllMain (
-    HANDLE hModule, DWORD dwReason, LPVOID lpReserved )
+    HINSTANCE hModule, DWORD dwReason, LPVOID lpReserved )
 {
     static DWORD dllHandleIndex;
     HMODULE dllHandle = 0;