diff --git a/media/libstagefright/NuCachedSource2.cpp b/media/libstagefright/NuCachedSource2.cpp
index 6727c734dc971..f29e7fb180050 100644
--- a/media/libstagefright/NuCachedSource2.cpp
+++ b/media/libstagefright/NuCachedSource2.cpp
@@ -267,6 +267,7 @@ void NuCachedSource2::onFetch() {
             mFetching = false;
         }
     } else {
+        Mutex::Autolock autoLock(mLock);
         restartPrefetcherIfNecessary_l();
     }