diff --git a/adb/fdevent/fdevent.h b/adb/fdevent/fdevent.h
index 9fc3b2c..bb3af74 100644
--- a/adb/fdevent/fdevent.h
+++ b/adb/fdevent/fdevent.h
@@ -79,8 +79,8 @@
     unique_fd Destroy(fdevent* fde);
 
   protected:
-    virtual void Register(fdevent*) {}
-    virtual void Unregister(fdevent*) {}
+    virtual void Register(fdevent*) = 0;
+    virtual void Unregister(fdevent*) = 0;
 
   public:
     // Change which events should cause notifications.
diff --git a/adb/fdevent/fdevent_poll.cpp b/adb/fdevent/fdevent_poll.cpp
index ac86c08..21c1ba0 100644
--- a/adb/fdevent/fdevent_poll.cpp
+++ b/adb/fdevent/fdevent_poll.cpp
@@ -211,3 +211,7 @@
         PLOG(FATAL) << "failed to write to fdevent interrupt fd";
     }
 }
+
+void fdevent_context_poll::Register(fdevent*) {}
+
+void fdevent_context_poll::Unregister(fdevent*) {}
diff --git a/adb/fdevent/fdevent_poll.h b/adb/fdevent/fdevent_poll.h
index 98abab2..8803e3e 100644
--- a/adb/fdevent/fdevent_poll.h
+++ b/adb/fdevent/fdevent_poll.h
@@ -48,6 +48,9 @@
     fdevent_context_poll();
     virtual ~fdevent_context_poll();
 
+    virtual void Register(fdevent* fde) final;
+    virtual void Unregister(fdevent* fde) final;
+
     virtual void Set(fdevent* fde, unsigned events) final;
 
     virtual void Loop() final;