diff --git a/ldap/xpcom/src/nsLDAPURL.cpp b/ldap/xpcom/src/nsLDAPURL.cpp
index fa93b05b4f..6a9beba2da 100644
--- a/ldap/xpcom/src/nsLDAPURL.cpp
+++ b/ldap/xpcom/src/nsLDAPURL.cpp
@@ -723,6 +723,12 @@ nsresult nsLDAPURL::SetQueryWithEncoding(const nsACString &aQuery, const mozilla
   return NS_MutateURI(mBaseURL).SetQueryWithEncoding(aQuery, aEncoding).Finalize(mBaseURL);
 }
 
+NS_IMETHODIMP_(void)
+nsLDAPURL::Serialize(mozilla::ipc::URIParams &aParams)
+{
+  mBaseURL->Serialize(aParams);
+}
+
 NS_IMPL_ISUPPORTS(nsLDAPURL::Mutator, nsIURISetters, nsIURIMutator)
 
 NS_IMETHODIMP
diff --git a/mailnews/addrbook/src/nsAddbookUrl.cpp b/mailnews/addrbook/src/nsAddbookUrl.cpp
index e62e80362c..01db9583f2 100644
--- a/mailnews/addrbook/src/nsAddbookUrl.cpp
+++ b/mailnews/addrbook/src/nsAddbookUrl.cpp
@@ -240,6 +240,12 @@ nsresult nsAddbookUrl::SetQueryWithEncoding(const nsACString &aQuery, const mozi
   return NS_MutateURI(m_baseURL).SetQueryWithEncoding(aQuery, aEncoding).Finalize(m_baseURL);
 }
 
+NS_IMETHODIMP_(void)
+nsAddbookUrl::Serialize(mozilla::ipc::URIParams &aParams)
+{
+  m_baseURL->Serialize(aParams);
+}
+
 NS_IMETHODIMP nsAddbookUrl::EqualsExceptRef(nsIURI *other, bool *_retval)
 {
   // The passed-in URI might be an nsMailtoUrl. Pass our inner URL to its
diff --git a/mailnews/base/util/nsMsgMailNewsUrl.cpp b/mailnews/base/util/nsMsgMailNewsUrl.cpp
index ac1dafa9e0..8eba4673a4 100644
--- a/mailnews/base/util/nsMsgMailNewsUrl.cpp
+++ b/mailnews/base/util/nsMsgMailNewsUrl.cpp
@@ -85,7 +85,6 @@ NS_INTERFACE_MAP_BEGIN(nsMsgMailNewsUrl)
   NS_INTERFACE_MAP_ENTRY(nsIURI)
   NS_INTERFACE_MAP_ENTRY(nsISerializable)
   NS_INTERFACE_MAP_ENTRY(nsIClassInfo)
-  NS_INTERFACE_MAP_ENTRY(nsIIPCSerializableURI)
   NS_INTERFACE_MAP_ENTRY_CONDITIONAL(nsIURIWithSpecialOrigin, m_hasNormalizedOrigin)
 NS_INTERFACE_MAP_END
 
@@ -97,12 +96,8 @@ NS_INTERFACE_MAP_END
 // cause problems in the future. See bug 1512356 and bug 1515337 for details,
 // follow-up in bug 1512698.
 
-//----------------------------------
-// Support for nsIIPCSerializableURI
-//----------------------------------
-void nsMsgMailNewsUrl::Serialize(mozilla::ipc::URIParams &aParams) {
-  nsCOMPtr<nsIIPCSerializableURI> serializable = do_QueryInterface(m_baseURL);
-  return serializable->Serialize(aParams);
+NS_IMETHODIMP_(void) nsMsgMailNewsUrl::Serialize(mozilla::ipc::URIParams &aParams) {
+  m_baseURL->Serialize(aParams);
 }
 
 //----------------------------
diff --git a/mailnews/base/util/nsMsgMailNewsUrl.h b/mailnews/base/util/nsMsgMailNewsUrl.h
index 70da49af15..adc8aeb310 100644
--- a/mailnews/base/util/nsMsgMailNewsUrl.h
+++ b/mailnews/base/util/nsMsgMailNewsUrl.h
@@ -28,7 +28,6 @@
 #include "nsIURIMutator.h"
 #include "nsISerializable.h"
 #include "nsIClassInfo.h"
-#include "nsIIPCSerializableURI.h"
 
 ///////////////////////////////////////////////////////////////////////////////////
 // Okay, I found that all of the mail and news url interfaces needed to support
@@ -44,8 +43,7 @@
 class NS_MSG_BASE nsMsgMailNewsUrl : public nsIMsgMailNewsUrl,
                                      public nsIURIWithSpecialOrigin,
                                      public nsISerializable,
-                                     public nsIClassInfo,
-                                     public nsIIPCSerializableURI
+                                     public nsIClassInfo
 {
 public:
     nsMsgMailNewsUrl();
@@ -57,7 +55,6 @@ public:
     NS_DECL_NSIURIWITHSPECIALORIGIN
     NS_DECL_NSISERIALIZABLE
     NS_DECL_NSICLASSINFO
-    NS_DECL_NSIIPCSERIALIZABLEURI
 
 protected:
   virtual nsresult Clone(nsIURI **_retval);
diff --git a/mailnews/compose/src/nsSmtpUrl.cpp b/mailnews/compose/src/nsSmtpUrl.cpp
index 26525f0f6e..94e34013b6 100644
--- a/mailnews/compose/src/nsSmtpUrl.cpp
+++ b/mailnews/compose/src/nsSmtpUrl.cpp
@@ -629,6 +629,12 @@ nsresult nsMailtoUrl::SetQueryWithEncoding(const nsACString &aQuery, const mozil
   return NS_MutateURI(m_baseURL).SetQueryWithEncoding(aQuery, aEncoding).Finalize(m_baseURL);
 }
 
+NS_IMETHODIMP_(void)
+nsMailtoUrl::Serialize(mozilla::ipc::URIParams &aParams)
+{
+  m_baseURL->Serialize(aParams);
+}
+
 NS_IMPL_ISUPPORTS(nsMailtoUrl::Mutator, nsIURISetters, nsIURIMutator)
 
 NS_IMETHODIMP