diff --git a/netwerk/base/src/nsSocketTransport.cpp b/netwerk/base/src/nsSocketTransport.cpp
index 07269a118cc8..0e912a9a53b3 100644
--- a/netwerk/base/src/nsSocketTransport.cpp
+++ b/netwerk/base/src/nsSocketTransport.cpp
@@ -124,6 +124,7 @@ nsSocketTransport::nsSocketTransport()
   mLock         = nsnull;
 
   mSuspendCount = 0;
+  mCancelOperation = PR_FALSE;
 
   mReadWriteState = 0;  
   SetReadType (eSocketRead_None);
@@ -289,6 +290,18 @@ nsresult nsSocketTransport::Process(PRInt16 aSelectFlags)
       continue;
     }
 
+    if (mCancelOperation) {
+      PR_LOG(gSocketLog, PR_LOG_DEBUG, 
+             ("Transport [this=%x] has been cancelled.\n", this));
+
+      // Cancel any read and/or write requests...
+      SetFlag(eSocketRead_Done);
+      SetFlag(eSocketWrite_Done);
+      mCurrentState = eSocketState_Done;
+
+      rv = NS_BINDING_ABORTED;
+    }
+
     switch (mCurrentState) {
       case eSocketState_Created:
       case eSocketState_Closed:
@@ -1060,7 +1073,15 @@ nsSocketTransport::Cancel(void)
 {
   nsresult rv = NS_OK;
 
-  rv = NS_ERROR_NOT_IMPLEMENTED;
+  // Enter the socket transport lock...
+  nsAutoLock aLock(mLock);
+
+  mCancelOperation = PR_TRUE;
+  //
+  // Wake up the transport on the socket transport thread so it can
+  // be removed from the select list...  
+  //
+  rv = mService->AddToWorkQ(this);
 
   PR_LOG(gSocketLog, PR_LOG_DEBUG, 
          ("Canceling nsSocketTransport [this=%x].  rv = %x\n",
diff --git a/netwerk/base/src/nsSocketTransport.h b/netwerk/base/src/nsSocketTransport.h
index e02dfb3c069a..52c76a23c86e 100644
--- a/netwerk/base/src/nsSocketTransport.h
+++ b/netwerk/base/src/nsSocketTransport.h
@@ -198,6 +198,7 @@ protected:
   PRUint32          mReadWriteState;
 
   PRInt32           mSuspendCount;
+  PRBool            mCancelOperation;
 
   PRFileDesc*   mSocketFD;
   PRNetAddr     mNetAddress;