diff --git a/libwvdrmengine/mediacrypto/Android.mk b/libwvdrmengine/mediacrypto/Android.mk
index 8cf087b6..a1955757 100644
--- a/libwvdrmengine/mediacrypto/Android.mk
+++ b/libwvdrmengine/mediacrypto/Android.mk
@@ -68,6 +68,8 @@ LOCAL_SHARED_LIBRARIES := \
   libhidlmemory \
   liblog
 
+LOCAL_CFLAGS := -Wthread-safety
+
 LOCAL_MODULE := libwvdrmcryptoplugin_hidl
 LOCAL_PROPRIETARY_MODULE := true
 
diff --git a/libwvdrmengine/mediacrypto/include_hidl/WVCryptoPlugin.h b/libwvdrmengine/mediacrypto/include_hidl/WVCryptoPlugin.h
index 1ea1fd4a..651c4a1a 100644
--- a/libwvdrmengine/mediacrypto/include_hidl/WVCryptoPlugin.h
+++ b/libwvdrmengine/mediacrypto/include_hidl/WVCryptoPlugin.h
@@ -5,9 +5,12 @@
 #ifndef WV_CRYPTO_PLUGIN_H_
 #define WV_CRYPTO_PLUGIN_H_
 
+#include <android-base/thread_annotations.h>
 #include <android/hardware/drm/1.0/ICryptoPlugin.h>
 #include <android/hidl/memory/1.0/IMemory.h>
 
+#include <mutex>
+
 #include "wv_content_decryption_module.h"
 #include "WVTypes.h"
 
@@ -58,13 +61,13 @@ struct WVCryptoPlugin : public ICryptoPlugin {
       const SharedBuffer& source,
       uint64_t offset,
       const DestinationBuffer& destination,
-      decrypt_cb _hidl_cb) override;
+      decrypt_cb _hidl_cb) override NO_THREAD_SAFETY_ANALYSIS; // use unique_lock
 
  private:
   WVDRM_DISALLOW_COPY_AND_ASSIGN_AND_NEW(WVCryptoPlugin);
 
   wvcdm::CdmSessionId mSessionId;
-  std::map<uint32_t, sp<IMemory> > mSharedBufferMap;
+  std::map<uint32_t, sp<IMemory> > mSharedBufferMap GUARDED_BY(mSharedBufferLock);
 
   sp<wvcdm::WvContentDecryptionModule> const mCDM;
 
@@ -74,6 +77,8 @@ struct WVCryptoPlugin : public ICryptoPlugin {
   static wvcdm::CdmResponseType countEncryptedBlocksInPatternedRange(
       size_t range, const Pattern& pattern, uint64_t* result);
   static void incrementIV(uint64_t increaseBy, std::vector<uint8_t>* ivPtr);
+
+  std::mutex mSharedBufferLock;
 };
 
 }  // namespace widevine
diff --git a/libwvdrmengine/mediacrypto/src_hidl/WVCryptoPlugin.cpp b/libwvdrmengine/mediacrypto/src_hidl/WVCryptoPlugin.cpp
index a97a6fa1..31c87b2f 100644
--- a/libwvdrmengine/mediacrypto/src_hidl/WVCryptoPlugin.cpp
+++ b/libwvdrmengine/mediacrypto/src_hidl/WVCryptoPlugin.cpp
@@ -98,6 +98,8 @@ Return<void> WVCryptoPlugin::setSharedBufferBase(
   sp<IMemory> hidlMemory = mapMemory(base);
   ALOGE_IF(hidlMemory == nullptr, "mapMemory returns nullptr");
 
+  std::lock_guard<std::mutex> shared_buffer_lock(mSharedBufferLock);
+
   // allow mapMemory to return nullptr
   mSharedBufferMap[bufferId] = hidlMemory;
   return Void();
@@ -114,7 +116,7 @@ Return<void> WVCryptoPlugin::decrypt(
     uint64_t offset,
     const DestinationBuffer& destination,
     decrypt_cb _hidl_cb) {
-
+    std::unique_lock<std::mutex> lock(mSharedBufferLock);
     if (mSharedBufferMap.find(source.bufferId) == mSharedBufferMap.end()) {
       _hidl_cb(Status::ERROR_DRM_CANNOT_HANDLE, 0,
                "source decrypt buffer base not set");
@@ -185,6 +187,9 @@ Return<void> WVCryptoPlugin::decrypt(
     destPtr = static_cast<void *>(handle);
   }
 
+  // release mSharedBufferLock
+  lock.unlock();
+
   // Calculate the output buffer size and determine if any subsamples are
   // encrypted.
   size_t destSize = 0;