diff --git a/extensions/webservices/soap/src/nsSOAPMessage.cpp b/extensions/webservices/soap/src/nsSOAPMessage.cpp
index 8d5a442d3025..0ef30b5e3115 100644
--- a/extensions/webservices/soap/src/nsSOAPMessage.cpp
+++ b/extensions/webservices/soap/src/nsSOAPMessage.cpp
@@ -244,7 +244,7 @@ NS_IMETHODIMP nsSOAPMessage::GetMethodName(nsAString & aMethodName)
       return NS_OK;
     }
   }
-  aMethodName.SetLength(0);
+  aMethodName.Truncate();
   return NS_OK;
 }
 
@@ -271,7 +271,7 @@ GetTargetObjectURI(nsAString & aTargetObjectURI)
       return encoding->GetInternalSchemaURI(temp, aTargetObjectURI);
     }
   }
-  aTargetObjectURI.SetLength(0);
+  aTargetObjectURI.Truncate();
   return NS_OK;
 }
 
diff --git a/extensions/webservices/soap/src/nsSOAPUtils.cpp b/extensions/webservices/soap/src/nsSOAPUtils.cpp
index 2c003ebd8cb6..bd3bb7148628 100644
--- a/extensions/webservices/soap/src/nsSOAPUtils.cpp
+++ b/extensions/webservices/soap/src/nsSOAPUtils.cpp
@@ -256,6 +256,7 @@ nsresult
     nsSOAPUtils::GetElementTextContent(nsIDOMElement * aElement,
                                        nsAString & aText)
 {
+  aText.Truncate();
   nsCOMPtr < nsIDOMNode > child;
   nsAutoString rtext;
   aElement->GetFirstChild(getter_AddRefs(child));
@@ -336,7 +337,7 @@ nsresult
                                  const nsAString & aQName,
                                  nsAString & aURI)
 {
-  aURI.Truncate(0);
+  aURI.Truncate();
   PRInt32 i = aQName.FindChar(':');
   if (i < 0) {
     return NS_OK;
@@ -415,7 +416,7 @@ nsresult
   else {
     externalURI.Assign(aURI);
   }
-  aPrefix.Truncate(0);
+  aPrefix.Truncate();
   if (externalURI.IsEmpty())
     return NS_OK;
   if (externalURI.Equals(nsSOAPUtils::kXMLNamespaceURI)) {
diff --git a/extensions/xmlextras/soap/src/nsSOAPMessage.cpp b/extensions/xmlextras/soap/src/nsSOAPMessage.cpp
index 8d5a442d3025..0ef30b5e3115 100644
--- a/extensions/xmlextras/soap/src/nsSOAPMessage.cpp
+++ b/extensions/xmlextras/soap/src/nsSOAPMessage.cpp
@@ -244,7 +244,7 @@ NS_IMETHODIMP nsSOAPMessage::GetMethodName(nsAString & aMethodName)
       return NS_OK;
     }
   }
-  aMethodName.SetLength(0);
+  aMethodName.Truncate();
   return NS_OK;
 }
 
@@ -271,7 +271,7 @@ GetTargetObjectURI(nsAString & aTargetObjectURI)
       return encoding->GetInternalSchemaURI(temp, aTargetObjectURI);
     }
   }
-  aTargetObjectURI.SetLength(0);
+  aTargetObjectURI.Truncate();
   return NS_OK;
 }
 
diff --git a/extensions/xmlextras/soap/src/nsSOAPUtils.cpp b/extensions/xmlextras/soap/src/nsSOAPUtils.cpp
index 2c003ebd8cb6..bd3bb7148628 100644
--- a/extensions/xmlextras/soap/src/nsSOAPUtils.cpp
+++ b/extensions/xmlextras/soap/src/nsSOAPUtils.cpp
@@ -256,6 +256,7 @@ nsresult
     nsSOAPUtils::GetElementTextContent(nsIDOMElement * aElement,
                                        nsAString & aText)
 {
+  aText.Truncate();
   nsCOMPtr < nsIDOMNode > child;
   nsAutoString rtext;
   aElement->GetFirstChild(getter_AddRefs(child));
@@ -336,7 +337,7 @@ nsresult
                                  const nsAString & aQName,
                                  nsAString & aURI)
 {
-  aURI.Truncate(0);
+  aURI.Truncate();
   PRInt32 i = aQName.FindChar(':');
   if (i < 0) {
     return NS_OK;
@@ -415,7 +416,7 @@ nsresult
   else {
     externalURI.Assign(aURI);
   }
-  aPrefix.Truncate(0);
+  aPrefix.Truncate();
   if (externalURI.IsEmpty())
     return NS_OK;
   if (externalURI.Equals(nsSOAPUtils::kXMLNamespaceURI)) {