diff --git a/mailnews/compose/src/nsMsgCompFields.cpp b/mailnews/compose/src/nsMsgCompFields.cpp
index 0b871b3d513f..e958c9ae2efe 100644
--- a/mailnews/compose/src/nsMsgCompFields.cpp
+++ b/mailnews/compose/src/nsMsgCompFields.cpp
@@ -613,7 +613,7 @@ nsresult nsMsgCompFields::AddForwardURL(const char* url)
 {
 	NS_ASSERTION(url && *url, "empty url");
 	if (!url || !*url)
-		return -1;
+		return NS_ERROR_NULL_POINTER;
 
 	if (m_numforward >= m_maxforward) {
 		m_maxforward += 10;