diff --git a/netwerk/protocol/http/nsHttpChannel.cpp b/netwerk/protocol/http/nsHttpChannel.cpp
index 1941b98d032..9f7cecf860c 100644
--- a/netwerk/protocol/http/nsHttpChannel.cpp
+++ b/netwerk/protocol/http/nsHttpChannel.cpp
@@ -3011,6 +3011,7 @@ nsHttpChannel::OnCacheEntryCheck(nsICacheEntry* entry, nsIApplicationCache* appC
             if (mDidReval) {
                 // Make the request unconditional again.
                 mRequestHead.ClearHeader(nsHttp::If_Modified_Since);
+                mRequestHead.ClearHeader(nsHttp::If_None_Match);
                 mRequestHead.ClearHeader(nsHttp::ETag);
                 mDidReval = false;
             }