diff --git a/netwerk/protocol/http/nsHttpHandler.cpp b/netwerk/protocol/http/nsHttpHandler.cpp
index a4e481fcac..3a5ec2936c 100644
--- a/netwerk/protocol/http/nsHttpHandler.cpp
+++ b/netwerk/protocol/http/nsHttpHandler.cpp
@@ -1362,10 +1362,10 @@ nsHttpHandler::PrefsChanged(nsIPrefBranch *prefs, const char *pref)
     }
 
     if (PREF_CHANGED(HTTP_PREF("spdy.chunk-size"))) {
-        // keep this within http/2 ranges of 1 to 2^14-1
+        // keep this within http/2 ranges of 1 to 2^24-1
         rv = prefs->GetIntPref(HTTP_PREF("spdy.chunk-size"), &val);
         if (NS_SUCCEEDED(rv))
-            mSpdySendingChunkSize = (uint32_t) clamped(val, 1, 0x3fff);
+            mSpdySendingChunkSize = (uint32_t) clamped(val, 1, 0xffffff);
     }
 
     // The amount of idle seconds on a spdy connection before initiating a