diff --git a/libshims/libshim_ui/Android.bp b/libshims/libshim_ui/Android.bp
index c0ac3c0..33c0dc5 100644
--- a/libshims/libshim_ui/Android.bp
+++ b/libshims/libshim_ui/Android.bp
@@ -8,6 +8,7 @@ cc_library_shared {
     name: "libshim_ui",
     shared_libs: [
         "libui",
+        "libsync",
         "libutils",
     ],
     srcs: [
diff --git a/libshims/libshim_ui/GraphicBufferMapper.cpp b/libshims/libshim_ui/GraphicBufferMapper.cpp
index a3ceffb..23b2c9c 100644
--- a/libshims/libshim_ui/GraphicBufferMapper.cpp
+++ b/libshims/libshim_ui/GraphicBufferMapper.cpp
@@ -5,6 +5,7 @@
  */
 
 #include <stdint.h>
+#include <sync/sync.h>
 #include <ui/GraphicBufferMapper.h>
 #include <ui/Rect.h>
 #include <utils/Errors.h>
@@ -19,4 +20,16 @@ status_t _ZN7android19GraphicBufferMapper4lockEPK13native_handlejRKNS_4RectEPPvP
     auto* gpm = static_cast<android::GraphicBufferMapper*>(thisptr);
     return gpm->lock(handle, usage, bounds, vaddr);
 }
+
+status_t _ZN7android19GraphicBufferMapper6unlockEPK13native_handle(void* thisptr,
+                                                                   buffer_handle_t handle) {
+    android::base::unique_fd outFence;
+    auto* gpm = static_cast<android::GraphicBufferMapper*>(thisptr);
+    status_t status = gpm->unlock(handle, &outFence);
+    if (status == android::OK && outFence.get() >= 0) {
+        sync_wait(outFence.get(), -1);
+        outFence.reset();
+    }
+    return status;
+}
 }