diff --git a/proprietary/wvm/WVMExtractorImpl.cpp b/proprietary/wvm/WVMExtractorImpl.cpp
index 5fb3a50e..7e874c7c 100644
--- a/proprietary/wvm/WVMExtractorImpl.cpp
+++ b/proprietary/wvm/WVMExtractorImpl.cpp
@@ -26,6 +26,7 @@ using namespace android;
 
 static sp<DecryptHandle> sDecryptHandle;
 static DrmManagerClient *sDrmManagerClient;
+static Mutex gWVMutex;
 
 static void _cb1(char *data, unsigned long size)
 {
@@ -88,6 +89,8 @@ bool IsWidevineMedia(const sp<DataSource>& dataSource) {
             ALOGV("IsWidevineMedia - insufficient data: %d", (int)bytesRead);
         } else {
             setenv("WV_SILENT", "true", 1);
+
+            Mutex::Autolock autoLock(gWVMutex);
             result = WV_IsWidevineMedia(buffer, kSniffSize);
         }
         delete[] buffer;
@@ -110,6 +113,8 @@ WVMExtractorImpl::WVMExtractorImpl(sp<DataSource> dataSource)
       mError(OK),
       mSetupStatus(OK)
 {
+    Mutex::Autolock autoLock(gWVMutex);
+
     dataSource->getDrmInfo(sDecryptHandle, &sDrmManagerClient);
 
     //ALOGD("WVMExtractorImpl::WVMExtractorImpl: uniqueId = %d", sDrmManagerClient->mUniqueId);