diff --git a/libwvdrmengine/cdm/core/src/oemcrypto_adapter_dynamic.cpp b/libwvdrmengine/cdm/core/src/oemcrypto_adapter_dynamic.cpp
index dc1cfb3e..99aa561d 100644
--- a/libwvdrmengine/cdm/core/src/oemcrypto_adapter_dynamic.cpp
+++ b/libwvdrmengine/cdm/core/src/oemcrypto_adapter_dynamic.cpp
@@ -21,6 +21,7 @@
 
 #include "level3.h"
 #include "log.h"
+#include "lock.h"
 #include "file_store.h"
 #include "properties.h"
 
@@ -314,6 +315,7 @@ class Adapter {
   }
 
   LevelSession get(OEMCrypto_SESSION session) {
+    AutoLock auto_lock(lookup_lock_);
     map_iterator pair = session_map_.find(session);
     if (pair == session_map_.end()) {
       return LevelSession();
@@ -322,6 +324,7 @@ class Adapter {
   }
 
   OEMCryptoResult OpenSession(OEMCrypto_SESSION* session, SecurityLevel level) {
+    AutoLock auto_lock(lookup_lock_);
     LevelSession new_session;
     OEMCryptoResult result;
     if (level == kLevelDefault && level1_valid_) {
@@ -344,6 +347,7 @@ class Adapter {
   }
 
   OEMCryptoResult CloseSession(OEMCrypto_SESSION session) {
+    AutoLock auto_lock(lookup_lock_);
     map_iterator pair = session_map_.find(session);
     if (pair == session_map_.end()) {
       return OEMCrypto_ERROR_INVALID_SESSION;
@@ -360,6 +364,7 @@ class Adapter {
   struct FunctionPointers level1_;
   struct FunctionPointers level3_;
   std::map<OEMCrypto_SESSION, LevelSession> session_map_;
+  Lock lookup_lock_;
   // This is just for debugging the map between session ids.
   // If we add this to the level 3 session id, then the external session
   // id will match the internal session id in the last two digits.