diff --git a/media/codec2/sfplugin/C2OMXNode.cpp b/media/codec2/sfplugin/C2OMXNode.cpp
index 962df0f..6ae1c13 100644
--- a/media/codec2/sfplugin/C2OMXNode.cpp
+++ b/media/codec2/sfplugin/C2OMXNode.cpp
@@ -287,7 +287,7 @@
         return UNKNOWN_ERROR;
     }
 
-    (void)mBufferIdsInUse.emplace(index, buffer);
+    mBufferIdsInUse.lock()->emplace(index, buffer);
     return OK;
 }
 
@@ -327,13 +327,19 @@
         ALOGD("Buffer source not set (index=%llu)", index.peekull());
         return;
     }
-    auto it = mBufferIdsInUse.find(index.peeku());
-    if (it == mBufferIdsInUse.end()) {
-        ALOGV("Untracked input index %llu (maybe already removed)", index.peekull());
-        return;
+
+    int32_t bufferId = 0;
+    {
+        decltype(mBufferIdsInUse)::Locked bufferIds(mBufferIdsInUse);
+        auto it = bufferIds->find(index.peeku());
+        if (it == bufferIds->end()) {
+            ALOGV("Untracked input index %llu (maybe already removed)", index.peekull());
+            return;
+        }
+        bufferId = it->second;
+        (void)bufferIds->erase(it);
     }
-    (void)mBufferSource->onInputBufferEmptied(it->second, -1);
-    (void)mBufferIdsInUse.erase(it);
+    (void)mBufferSource->onInputBufferEmptied(bufferId, -1);
 }
 
 }  // namespace android
diff --git a/media/codec2/sfplugin/C2OMXNode.h b/media/codec2/sfplugin/C2OMXNode.h
index b7bd696..3ca6c0a 100644
--- a/media/codec2/sfplugin/C2OMXNode.h
+++ b/media/codec2/sfplugin/C2OMXNode.h
@@ -20,9 +20,10 @@
 #include <atomic>
 
 #include <android/IOMXBufferSource.h>
+#include <codec2/hidl/client.h>
+#include <media/stagefright/foundation/Mutexed.h>
 #include <media/IOMX.h>
 #include <media/OMXBuffer.h>
-#include <codec2/hidl/client.h>
 
 namespace android {
 
@@ -111,7 +112,7 @@
     c2_cntr64_t mPrevInputTimestamp; // input timestamp for previous frame
     c2_cntr64_t mPrevCodecTimestamp; // adjusted (codec) timestamp for previous frame
 
-    std::map<uint64_t, buffer_id> mBufferIdsInUse;
+    Mutexed<std::map<uint64_t, buffer_id>> mBufferIdsInUse;
 };
 
 }  // namespace android