diff --git a/mozilla/modules/libreg/xpcom/nsRegistry.cpp b/mozilla/modules/libreg/xpcom/nsRegistry.cpp
index 6f211574292..29ca33064cc 100644
--- a/mozilla/modules/libreg/xpcom/nsRegistry.cpp
+++ b/mozilla/modules/libreg/xpcom/nsRegistry.cpp
@@ -447,7 +447,7 @@ NS_IMETHODIMP nsRegistry::OpenWellKnownRegistry( nsWellKnownRegistry regid ) {
             directoryService->Get("xpcom.currentProcess.componentRegistry", NS_GET_IID(nsIFile), 
                                           getter_AddRefs(registryLocation));
 
-            if (registryLocation != nsnull)
+            if (registryLocation)
             {
                 foundReg = PR_TRUE;
                 registryLocation->GetPath(&regFile);  // dougt fix...
diff --git a/mozilla/xpcom/components/nsRegistry.cpp b/mozilla/xpcom/components/nsRegistry.cpp
index 6f211574292..29ca33064cc 100644
--- a/mozilla/xpcom/components/nsRegistry.cpp
+++ b/mozilla/xpcom/components/nsRegistry.cpp
@@ -447,7 +447,7 @@ NS_IMETHODIMP nsRegistry::OpenWellKnownRegistry( nsWellKnownRegistry regid ) {
             directoryService->Get("xpcom.currentProcess.componentRegistry", NS_GET_IID(nsIFile), 
                                           getter_AddRefs(registryLocation));
 
-            if (registryLocation != nsnull)
+            if (registryLocation)
             {
                 foundReg = PR_TRUE;
                 registryLocation->GetPath(&regFile);  // dougt fix...
diff --git a/mozilla/xpcom/io/nsLocalFileCommon.cpp b/mozilla/xpcom/io/nsLocalFileCommon.cpp
index 7d53218790b..a63c0bcd77e 100644
--- a/mozilla/xpcom/io/nsLocalFileCommon.cpp
+++ b/mozilla/xpcom/io/nsLocalFileCommon.cpp
@@ -128,8 +128,8 @@ nsFSStringConversion::PrepareFSCharset()
    { 
      // lazy eval of the file system charset
      NS_WITH_SERVICE(nsIPlatformCharset, pcharset, NS_PLATFORMCHARSET_PROGID, &res);
-     NS_ASSERTION((NS_SUCCEEDED(res) && (nsnull != pcharset)), "cannot get platform charset");
-     if(NS_SUCCEEDED(res) && (nsnull != pcharset)) {
+     NS_ASSERTION((NS_SUCCEEDED(res) && pcharset), "cannot get platform charset");
+     if(NS_SUCCEEDED(res) && pcharset) {
         res = pcharset->GetCharset(kPlatformCharsetSel_FileName, mFSCharset);
      } 
    }
@@ -139,17 +139,17 @@ NS_IMETHODIMP
 nsFSStringConversion::PrepareEncoder()
 {
    nsresult res = NS_OK;
-   if(nsnull == mEncoder)
+   if(! mEncoder)
    {
        res = PrepareFSCharset();
        if(NS_SUCCEEDED(res)) {
            NS_WITH_SERVICE(nsICharsetConverterManager,
                 ucmgr, NS_CHARSETCONVERTERMANAGER_PROGID, &res);
-           NS_ASSERTION((NS_SUCCEEDED(res) && (nsnull != ucmgr)), 
+           NS_ASSERTION((NS_SUCCEEDED(res) && ucmgr), 
                    "cannot get charset converter manager ");
-           if(NS_SUCCEEDED(res) && (nsnull != ucmgr)) 
+           if(NS_SUCCEEDED(res) && ucmgr) 
                res = ucmgr->GetUnicodeEncoder( &mFSCharset, getter_AddRefs(mEncoder));
-           NS_ASSERTION((NS_SUCCEEDED(res) && (nsnull != mEncoder)), 
+           NS_ASSERTION((NS_SUCCEEDED(res) && mEncoder), 
                    "cannot find the unicode encoder");
        }
    }
@@ -159,17 +159,17 @@ NS_IMETHODIMP
 nsFSStringConversion::PrepareDecoder()
 {
    nsresult res = NS_OK;
-   if(nsnull == mDecoder)
+   if(! mDecoder)
    {
        res = PrepareFSCharset();
        if(NS_SUCCEEDED(res)) {
            NS_WITH_SERVICE(nsICharsetConverterManager,
                 ucmgr, NS_CHARSETCONVERTERMANAGER_PROGID, &res);
-           NS_ASSERTION((NS_SUCCEEDED(res) && (nsnull != ucmgr)), 
+           NS_ASSERTION((NS_SUCCEEDED(res) && ucmgr), 
                    "cannot get charset converter manager ");
-           if(NS_SUCCEEDED(res) && (nsnull != ucmgr)) 
+           if(NS_SUCCEEDED(res) && ucmgr) 
                res = ucmgr->GetUnicodeDecoder( &mFSCharset, getter_AddRefs(mDecoder));
-           NS_ASSERTION((NS_SUCCEEDED(res) && (nsnull != mDecoder)), 
+           NS_ASSERTION((NS_SUCCEEDED(res) && mDecoder), 
                    "cannot find the unicode decoder");
        }
    }
diff --git a/mozilla/xpcom/proxy/src/nsProxyObjectManager.cpp b/mozilla/xpcom/proxy/src/nsProxyObjectManager.cpp
index be9fd25fba8..ff97a6fe59a 100644
--- a/mozilla/xpcom/proxy/src/nsProxyObjectManager.cpp
+++ b/mozilla/xpcom/proxy/src/nsProxyObjectManager.cpp
@@ -121,7 +121,7 @@ nsProxyObjectManager::~nsProxyObjectManager()
 nsProxyObjectManager *
 nsProxyObjectManager::GetInstance()
 {
-    if (mInstance == nsnull) 
+    if (! mInstance) 
     {
         mInstance = new nsProxyObjectManager();
     }
@@ -163,7 +163,7 @@ nsProxyObjectManager::GetProxyObject(nsIEventQueue *destQueue, REFNSIID aIID, ns
     
     // check to see if the eventQ is on our thread.  If so, just return the real object.
     
-    if (postQ != nsnull && !(proxyType & PROXY_ASYNC) && !(proxyType & PROXY_ALWAYS))
+    if (postQ && !(proxyType & PROXY_ASYNC) && !(proxyType & PROXY_ALWAYS))
     {
         PRBool aResult;
         postQ->IsQueueOnCurrentThread(&aResult);