1 files changed, 1 insertions, 0 deletions
diff --git a/mailnews/imap/src/nsImapProtocol.cpp b/mailnews/imap/src/nsImapProtocol.cpp
index 9114a28f2..5e2639a5a 100644
--- a/mailnews/imap/src/nsImapProtocol.cpp
+++ b/mailnews/imap/src/nsImapProtocol.cpp
@@ -3806,6 +3806,7 @@ nsImapProtocol::PostLineDownLoadEvent(const char *line, uint32_t uidOfMessage)
 void nsImapProtocol::HandleMessageDownLoadLine(const char *line, bool isPartialLine,
                                                char *lineCopy)
 {
+  NS_ENSURE_TRUE_VOID(line);
   NS_PRECONDITION(lineCopy == nullptr || !PL_strcmp(line, lineCopy),
                   "line and lineCopy must contain the same string");
   const char *messageLine = line;