diff --git a/CASA-auth-token/client/library/engine.c b/CASA-auth-token/client/library/engine.c
index 173918d8..0f598f47 100644
--- a/CASA-auth-token/client/library/engine.c
+++ b/CASA-auth-token/client/library/engine.c
@@ -1367,14 +1367,17 @@ UnInitializeLibrary(void)
    }
 
    pListEntry = g_ATSHostList.Flink;
-   while (pListEntry != &g_ATSHostList)
+   if (pListEntry)
    {
-       pHostEntry = CONTAINING_RECORD(pListEntry, ATSHostEntry, listEntry);
-       RemoveEntryList(pListEntry);
-       free(pHostEntry->pNameAndPort);
-       free(pHostEntry->pName);
-       free(pHostEntry);
-       pListEntry = g_ATSHostList.Flink;
+      while (pListEntry != &g_ATSHostList)
+      {
+         pHostEntry = CONTAINING_RECORD(pListEntry, ATSHostEntry, listEntry);
+         RemoveEntryList(pListEntry);
+         free(pHostEntry->pNameAndPort);
+         free(pHostEntry->pName);
+         free(pHostEntry);
+         pListEntry = g_ATSHostList.Flink;
+      }
    }
 
    DbgTrace(1, "-UnInitializeLibrary- End\n", 0);