diff --git a/libs/hwc2on1adapter/HWC2On1Adapter.cpp b/libs/hwc2on1adapter/HWC2On1Adapter.cpp
index e1b9a8a..77f06bb 100644
--- a/libs/hwc2on1adapter/HWC2On1Adapter.cpp
+++ b/libs/hwc2on1adapter/HWC2On1Adapter.cpp
@@ -426,7 +426,13 @@
 
     std::unique_lock<std::recursive_timed_mutex> lock(mStateMutex);
 
-    mCallbacks[descriptor] = {callbackData, pointer};
+    if (pointer != nullptr) {
+        mCallbacks[descriptor] = {callbackData, pointer};
+    } else {
+        ALOGI("unregisterCallback(%s)", to_string(descriptor).c_str());
+        mCallbacks.erase(descriptor);
+        return Error::None;
+    }
 
     bool hasPendingInvalidate = false;
     std::vector<hwc2_display_t> displayIds;