diff --git a/mozilla/xpcom/base/nsISupportsUtils.h b/mozilla/xpcom/base/nsISupportsUtils.h
index 95a9a39bda4..f7190a7d492 100644
--- a/mozilla/xpcom/base/nsISupportsUtils.h
+++ b/mozilla/xpcom/base/nsISupportsUtils.h
@@ -554,4 +554,18 @@ NS_IMETHODIMP _class::QueryInterface(REFNSIID aIID, void** aInstancePtr)      \
 
 ////////////////////////////////////////////////////////////////////////////////
 
+// A type-safe interface for calling |QueryInterface()|.  A similar implementation
+//	exists in "nsCOMPtr.h" for use with |nsCOMPtr|s.
+
+template <class T>
+inline
+nsresult
+CallQueryInterface( nsISupports* aSource, T** aDestination )
+		// a type-safe shortcut for calling the |QueryInterface()| member function
+	{
+		NS_PRECONDITION(aSource, "null parameter");
+
+		return aSource->QueryInterface(T::GetIID(), aDestination);
+	}
+
 #endif /* __nsISupportsUtils_h */
diff --git a/mozilla/xpcom/glue/nsISupportsUtils.h b/mozilla/xpcom/glue/nsISupportsUtils.h
index 95a9a39bda4..f7190a7d492 100644
--- a/mozilla/xpcom/glue/nsISupportsUtils.h
+++ b/mozilla/xpcom/glue/nsISupportsUtils.h
@@ -554,4 +554,18 @@ NS_IMETHODIMP _class::QueryInterface(REFNSIID aIID, void** aInstancePtr)      \
 
 ////////////////////////////////////////////////////////////////////////////////
 
+// A type-safe interface for calling |QueryInterface()|.  A similar implementation
+//	exists in "nsCOMPtr.h" for use with |nsCOMPtr|s.
+
+template <class T>
+inline
+nsresult
+CallQueryInterface( nsISupports* aSource, T** aDestination )
+		// a type-safe shortcut for calling the |QueryInterface()| member function
+	{
+		NS_PRECONDITION(aSource, "null parameter");
+
+		return aSource->QueryInterface(T::GetIID(), aDestination);
+	}
+
 #endif /* __nsISupportsUtils_h */
diff --git a/mozilla/xpcom/public/nsISupportsUtils.h b/mozilla/xpcom/public/nsISupportsUtils.h
index 95a9a39bda4..f7190a7d492 100644
--- a/mozilla/xpcom/public/nsISupportsUtils.h
+++ b/mozilla/xpcom/public/nsISupportsUtils.h
@@ -554,4 +554,18 @@ NS_IMETHODIMP _class::QueryInterface(REFNSIID aIID, void** aInstancePtr)      \
 
 ////////////////////////////////////////////////////////////////////////////////
 
+// A type-safe interface for calling |QueryInterface()|.  A similar implementation
+//	exists in "nsCOMPtr.h" for use with |nsCOMPtr|s.
+
+template <class T>
+inline
+nsresult
+CallQueryInterface( nsISupports* aSource, T** aDestination )
+		// a type-safe shortcut for calling the |QueryInterface()| member function
+	{
+		NS_PRECONDITION(aSource, "null parameter");
+
+		return aSource->QueryInterface(T::GetIID(), aDestination);
+	}
+
 #endif /* __nsISupportsUtils_h */