diff --git a/dali/base/dadfs.cpp b/dali/base/dadfs.cpp
index 1526640ca49..dbd1738589c 100644
--- a/dali/base/dadfs.cpp
+++ b/dali/base/dadfs.cpp
@@ -8239,20 +8239,19 @@ class CNamedGroupStore: implements INamedGroupStore, public CInterface
 
 };
 
-static CNamedGroupStore *groupStore = NULL;
-static CriticalSection groupsect;
+static std::atomic<CNamedGroupStore *> groupStore{nullptr};
 
 bool CNamedGroupIterator::match()
 {
     if (conn.get()) {
         if (matchgroup.get()) {
-            if (!groupStore)
+            if (!groupStore.load())
                 return false;
             const char *name = pe->query().queryProp("@name");
             if (!name||!*name)
                 return false;
             GroupType dummy;
-            Owned<IGroup> lgrp = groupStore->dolookup(name, conn, NULL, dummy);
+            Owned<IGroup> lgrp = groupStore.load()->dolookup(name, conn, NULL, dummy);
             if (lgrp) {
                 if (exactmatch)
                     return lgrp->equals(matchgroup);
@@ -8266,14 +8265,11 @@ bool CNamedGroupIterator::match()
     return false;
 }
 
-INamedGroupStore  &queryNamedGroupStore()
+INamedGroupStore &queryNamedGroupStore()
 {
-    if (!groupStore) {
-        CriticalBlock block(groupsect);
-        if (!groupStore)
-            groupStore = new CNamedGroupStore();
-    }
-    return *groupStore;
+    if (!groupStore.load())
+        groupStore.store(new CNamedGroupStore());
+    return *(groupStore.load());
 }
 
 // --------------------------------------------------------
@@ -9204,8 +9200,7 @@ GetFileClusterNamesType CDistributedFileDirectory::getFileClusterNames(const cha
 // --------------------------------------------------------
 
 
-static CDistributedFileDirectory *DFdir = NULL;
-static CriticalSection dfdirCrit;
+static std::atomic<CDistributedFileDirectory *> DFdir{nullptr};
 
 /**
  * Public method to control DistributedFileDirectory access
@@ -9214,12 +9209,9 @@ static CriticalSection dfdirCrit;
  */
 IDistributedFileDirectory &queryDistributedFileDirectory()
 {
-    if (!DFdir) {
-        CriticalBlock block(dfdirCrit);
-        if (!DFdir)
-            DFdir = new CDistributedFileDirectory();
-    }
-    return *DFdir;
+    if (!DFdir.load())
+        DFdir.store(new CDistributedFileDirectory());
+    return *DFdir.load();
 }
 
 /**
@@ -9227,25 +9219,29 @@ IDistributedFileDirectory &queryDistributedFileDirectory()
  */
 void closedownDFS()  // called by dacoven
 {
-    CriticalBlock block(dfdirCrit);
-    try {
-        delete DFdir;
-    }
-    catch (IMP_Exception *e) {
-        if (e->errorCode()!=MPERR_link_closed)
-            throw;
-        PrintExceptionLog(e,"closedownDFS");
-        e->Release();
+    if (DFdir.load())
+    {
+        try {
+            delete DFdir.load();
+        }
+        catch (IMP_Exception *e) {
+            if (e->errorCode()!=MPERR_link_closed)
+                throw;
+            PrintExceptionLog(e,"closedownDFS");
+            e->Release();
+        }
+        catch (IDaliClient_Exception *e) {
+            if (e->errorCode()!=DCERR_server_closed)
+                throw;
+            e->Release();
+        }
+        DFdir.store(nullptr);
     }
-    catch (IDaliClient_Exception *e) {
-        if (e->errorCode()!=DCERR_server_closed)
-            throw;
-        e->Release();
+    if (groupStore.load())
+    {
+        ::Release(groupStore.load());
+        groupStore.store(nullptr);
     }
-    DFdir = NULL;
-    CriticalBlock block2(groupsect);
-    ::Release(groupStore);
-    groupStore = NULL;
 }
 
 class CDFPartFilter : implements IDFPartFilter, public CInterface