--- a/mobile/android/app/mobile.js
+++ b/mobile/android/app/mobile.js
@@ -103,16 +103,20 @@ pref("network.http.keep-alive.timeout", 
 pref("network.http.max-connections", 20);
 pref("network.http.max-persistent-connections-per-server", 6);
 pref("network.http.max-persistent-connections-per-proxy", 20);
 
 // spdy
 pref("network.http.spdy.push-allowance", 32768);
 pref("network.http.spdy.default-hpack-buffer", 4096); // 4k
 
+// Racing the cache with the network should be disabled to prevent accidental
+// data usage.
+pref("network.http.rcwn.enabled", false);
+
 // See bug 545869 for details on why these are set the way they are
 pref("network.buffer.cache.count", 24);
 pref("network.buffer.cache.size",  16384);
 
 // predictive actions
 pref("network.predictor.enabled", true);
 pref("network.predictor.max-db-size", 2097152); // bytes
 pref("network.predictor.preserve", 50); // percentage of predictor data to keep when cleaning up

--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -1620,17 +1620,17 @@ pref("network.http.enforce-framing.soft"
 // the network will exist in header array as empty string. Call SetHeader with
 // an empty value will still delete the header.(Bug 6699259)
 pref("network.http.keep_empty_response_headers_as_empty_string", true);
 
 // Max size, in bytes, for received HTTP response header.
 pref("network.http.max_response_header_size", 393216);
 
 // If we should attempt to race the cache and network
-pref("network.http.rcwn.enabled", true);
+pref("network.http.rcwn.enabled", false);
 pref("network.http.rcwn.cache_queue_normal_threshold", 50);
 pref("network.http.rcwn.cache_queue_priority_threshold", 10);
 
 // default values for FTP
 // in a DSCP environment this should be 40 (0x28, or AF11), per RFC-4594,
 // Section 4.8 "High-Throughput Data Service Class", and 80 (0x50, or AF22)
 // per Section 4.7 "Low-Latency Data Service Class".
 pref("network.ftp.data.qos", 0);