diff --git a/services/surfaceflinger/DisplayHardware/HWC2On1Adapter.cpp b/services/surfaceflinger/DisplayHardware/HWC2On1Adapter.cpp
index 617ea9f..7f48289 100644
--- a/services/surfaceflinger/DisplayHardware/HWC2On1Adapter.cpp
+++ b/services/surfaceflinger/DisplayHardware/HWC2On1Adapter.cpp
@@ -1993,9 +1993,8 @@
     mHasUnsupportedDataspace(false),
     mHasUnsupportedPlaneAlpha(false) {}
 
-bool HWC2On1Adapter::SortLayersByZ::operator()(
-        const std::shared_ptr<Layer>& lhs, const std::shared_ptr<Layer>& rhs)
-{
+bool HWC2On1Adapter::SortLayersByZ::operator()(const std::shared_ptr<Layer>& lhs,
+                                               const std::shared_ptr<Layer>& rhs) const {
     return lhs->getZ() < rhs->getZ();
 }
 
diff --git a/services/surfaceflinger/DisplayHardware/HWC2On1Adapter.h b/services/surfaceflinger/DisplayHardware/HWC2On1Adapter.h
index 962361e..45922af 100644
--- a/services/surfaceflinger/DisplayHardware/HWC2On1Adapter.h
+++ b/services/surfaceflinger/DisplayHardware/HWC2On1Adapter.h
@@ -123,7 +123,7 @@
     class SortLayersByZ {
         public:
             bool operator()(const std::shared_ptr<Layer>& lhs,
-                    const std::shared_ptr<Layer>& rhs);
+                    const std::shared_ptr<Layer>& rhs) const;
     };
 
     class DisplayContentsDeleter {